A curtain wall is the same as an extension shield except:
1) You can't fuck up and get caught out on a technicality
2) Unlike extension abuse, you don't need to actively be there to extend it
3) It's less convoluted, so more people will do it
Counter-catapults:
1) Counter-catapults (as far as I know?) get to still exist, which is dumb for obvious reasons when they've a 24 hour dry time
2) Counter-catapults, if your village is designed correctly, can have the same range as offensive catapults
In legacy my main village had 3 curtain walls, and enough honeycomb to where 8 days of sieging would be required to get everything. I lived nearby Ainran, which I believe had 6 walls. Most significant groups had curtain walls.
That was legacy, when you needed to make a poopload of bricks for a relatively small bwalls. Nowdays, you only need palisades that cost like 3 blocks per segment, when you can get over 100 blocks of wood from a single log.
I don't see it being feasible to raid anybody who's remotely motivated and prepared to defend, irrespective of their combat stats