As it is right now, without collecting 50 candleberries or 100 honeycombs, you cannot:
- Get hard metal stuff - This is the obvious one, and clearly intended. You're locked out of swords (all kinds) and the only spear, heavy armors, and various hard metal odds and ends.
- Get most soft metal stuff - This is a very frustrating one. When you finally get your hands on metal, previously one of the major progression steps, you check your recipes one by one and see...nope, requires an anvil. Nope, requires an anvil too. Nope, that also can't be made without an anvil. Hammer and anvil is required for most things metal, and you don't get it until you hit layer 2 now. The only truly major breakthrough you still get from soft metal is being able to build mine supports; the once legendary wooden chest upgrade has been rendered nigh-obsolete by great natural containers (especially the Jotun Clam, which essentially invalidates portable container progression entirely).
- Craft glass - The impopular change to require a glass blowing rod and lye had another side effect: glass is entirely dependent on hard metal (as you need an anvil to craft the glass blowing rod), so since W14, glass is now entirely dependent on collecting 50 candleberries or 100 honeycombs. (Side note: historically, glassmaking long predates ironworking, which makes it even more ridiculous.) This obviously affects typical glass items, but it also cascades into things like not being able to...
- Perform proper alchemy - From way before you have any metal (or even cloth or whatever), you can start creating elixirs by mixing things essentially at random and hoping to find a good overlap somewhere. However, every tool required in refining ingredients - retort, tripod burner, burette, testtube rack - requires either glass or hard metal, meaning you're entirely locked into 'use all effects' elixirs until you can suddenly do nearly everything else.
- Make sausages - The ceramic meat grinder has yet to make its return, so while we're stacking up tons of intestines we can't use (I can defeat boars in a fair fight without taking wounds, but don't have 10 wax), we remain unable to use them for sausages. Not even kebab can be made until you go deeper underground.
- Travel across oceans, or carry a lot of cargo during naval journeys - It used to be that cloth production was very interesting to work towards as it had a major payoff in the form of a snekkja (or before that, a knarr), but I have more than enough cloth for one now and the only impressive thing I can do with it (that I couldn't do with my smaller first batch of cloth) is build barter stands, which without coins (layer 3) are barely functional (as few people are interested in whatever 1:1 trades you offer, and you need coins to specifiy 'I need X, Y or Z, and will offer A, B and/or C in return'; you also can't use them to buy things you don't have yet (e.g. hard metal)).
- Build a cellar - This is kinda under 'hard metal stuff', but it's notable that the extra storage space (without taking extra space on your claim) has been delayed until a fairly late point. As a hermit, I always have to build multiple buildings just to stash my stuff. (This actually goes further into the tedium of storage management being a problem, but that's too big of a subject to handle here.)
- Summon nidbanes - As nidbane fetters require hard metal. Thus, anyone can steal or vandalize the property of players who haven't reached the second layer yet without any risk of getting nidbanes sent after them.
- Get wine or beer - As they require demijohns, which require glass. (Vinegar can fortunately still be made using buckets.) (EDIT: Can be made without a glass blowing rod, so not dependent on hard metal.)
- Build mine supports without carrying in wood from the outside - As only wooden mine supports can be built without hard metal. It's a minor thing, but it adds tedium, which now lasts significantly longer.
- Craft coade clay - Which, again, requires glass. This is fortunately a moot point due to a different change unrelated to metal that's crept in:
Beyond the metal issue itself, there is one other thing that requires layer 2+ nowadays: you need deeper layers to get higher quality stones, and you need higher quality stones to get sharp tools beyond top natural clay quality. Tool quality nowadays hardcaps quality of all animal products, so I've hit a hard cap on anything you get from hunting that can't be resolved until I reach layer 2. (Theoretically you could farm for weeks to get string and wood of a high enough quality to surpass that limit, but that's beyond impractical.)
Now, here's the real kicker: as a hermit, when I finally do reach layer 2, I unlock everything at the same time. I've had so much time to prepare, all of these things that were once small individual steps become available to me all at once, to the point where there's barely anything I wanted to accomplish left. Thinking back to the previous couple of worlds, I think this was what caused me to gradually stop playing every time. Everything's been accomplished, all at once; why keep playing? I can finally sail the world in my Snekkja, but what can I still discover that's worth the effort? I can create spectacles, but my PER*EXP already lets me see everything. I could make sausages, but I'm not capping anything with my stats anymore. Mining has become easier, but I already have all the metal I need. All that's left to do is to grind quality...and go back to collecting 50 more candleberries to take the only major progression step still available to me now.