Many people complain that there should not be a level-limit to anvils. However, I have never encountered this issue IF I’m using it properly. I have made the perfect armor / tools with all the best enchants multiple times (on vanilla), and if you combine the books in the correct order, you never reach the limit.
The problem comes when repairing. It will cost more and more levels until it will not let you because “too expensive”. If a person has repaired that many times they have a XP farm already, the cap is not necessary and serves 0 purpose.
So this problem occurs if people don’t have access to mending, which I can understand in the early game. In the mid to late game, people usually have access to mending.
So this is mostly a problem for servers which don’t have mending or for new players I assume.