Those rules are set by tournament directors, not Chess.com. Many members like them because they exclude new/ slow players who often gum up tournaments.
Many tournaments have other requirements too- about average response time/ move and timeout percentage.
Chess.com runs its own tournaments but most tournaments are started by members. You should ask the TD's involved.
This is explained on the Help pages- https://support.chess.com/customer/en/portal/articles/1444863-who-is-allowed-to-join-a-tournament-
You will understand these rules and probably agree with them once you have more...experience.
Dear Chess.com,
Actually this minimum is not advertised in the tournament pages. I used to have a chess.com account a couple of year ago, now payed for a diamond membership to be able to play tournaments, just to discover that most of them won't allow me for not having played enough games.
All tournaments I pressed enter today didn't allow me, one required 10, another 144 and another 20. I feel like a fool for having payed for an account if I can't benefit from it, since I can play online chess games outside tournaments with a free account too..