I can only speak for D1A but I'm not sure it's been better since I started in Wilk - 45 of top 48 teams from last season are filled and can make Immediate moves to find themselves in Top 32 + 11 more coaches that are in rebuild mode that should be able to build into Top 32 within 3 seasons (or find an opening they can be comfortable in)
I know 100 seasons ago the whole world was full but that's not realistic at the current level of WiS interest in growth. I think the D1A worlds are seeing small growth across the board.
I've also seen a new group of excited players in D3 I the Discord and that's a nice new base for seasons to co.e no matter which level they find to be their favorite.