Could you elaborate on the bolded part?
I'm looking at this solely through the prism of "what would be more effective at improving the upwards mobility of clubs", and not a holistic overview of how I personally think the game should look like going forward. Basically any legislation that promotes the sporting side over the financial one when it comes to winning, to any extent large or small. It could be as radical as a wage cap in one of its many forms, squad based restrictions designed to deal with the stockpiling of players, a system designed around requiring a set amount of academy players. There are pros and cons to all of these, but unlike the City method they will would hypothetically effect all clubs. I need to stress that I'm not saying this should or shouldn't happen, just that if granting greater opportunities for smaller clubs to rise is the aim, there are more effective ways than eliminating financial oversight.
What City have done isn't based on closing the gap between the elite clubs and the non-elite in a widespread sense, there was no policy implemented designed to improve the chances of clubs rising in stature. They just won the lottery. They've made some great footballing decisions and play some wonderful football, but it's not something that can be emulated. Supporters have to cross their fingers and hope a billionaire purchases their club.
The EFL is more of a mess as well. Derby were lucky to avoid liquidation, and there are many other clubs with precarious financial situations. By trying to keep up with the clubs with wealthy owners, many of the clubs are gambling their futures. Covid compounded these issues, but it's a serious problem.