I agree with you, football teams that get promoted to the 1st division Should have a sufficient budget to sign high level players and coaches, in fact in the PL we realized that Whoever pushes from the middle of the season and gets a good score has a good chance of winning the PL , more so in this season where City went down like a ravine, now things are getting better, what I like about the PL is the Physical level of demand, it's the best.
But, not all have the financial ability as you mentioned. some of them who are promoted to the top league just hope to stay in the premier league as long as possible even though they can't get the title or unable to sign top level player and coach. At the first, tt's hard to get sponsors if they don't have star players, they need several seasons to get high value sponsors if they are able to stay in the top league.