There are other managers who are as capable of working with a limited budget, you could even argue that managers who are more open to using modern data driven recruitment (no, not just the failed AI attempt which people on here hate despite not fully understanding). But a system similar to that used very successfully by other clubs.
The fitness issues weren't just this season, we've suffered from a lack of fitness when Wilder & co had a pre-seasons, we've seen nothing to suggest there will be an improvement in those terms next season. Yes our overall fitness was good in his first spell, but since covid it's been poor even with when he's had pre-season.
I agree the infrastructure behind the scenes needs work for us to progress, but that won't happen with Wilder in charge so we have to just move on at some point. We all know he would refuse to work with a sporting director or without full control so we can't progress while he's here blocking that progress. We're also currently limited by Bettis being so involved and seemingly mates with Wilder.
There's also the issue that if we do progress, at some point we will need to sign better players and therefore pay higher fees. Wilder has proven, several times, that he cannot be trusted with those funds.
Personally I think if the owners had an ambition (or knowledge of the game) they would make the required changes, bring in the correct people/set up behind the scenes and tell Wilder he can either work within that set up as the head coach or he can leave of his own accord.