Bobby, Salah and Mane were already established footballers with their best years ahead of them in which we spent, at the time, a significant amount of money to be a first XI starter. These weren't just wing it on the cheap transfers for cover and hope of improvement as intimating that's what they were is just not accurate.
If we had signed Fekir at the rumored numbers it was to be a starter as you're not spending that type of money for any other reason.
Now you can then state that due to the improved starters your bench is better and your squad isn't as thin, year over year the holes keep getting smaller which is exactly what we're doing. But that doesn't mean that there won't be instances where we're sitting here wishing one more player was bought because of form, suspension or injuries and it will probably be like that for a good many years to go if not longer.
Of course they were established footballers and there is no cheap bargain signings today [bar Shaqiri and Robertson, exceptions to the rule in today's market] HOWEVER they were NOT on the level they are currently. They weren't unknowns, but they weren't top of the food chain, they've improved, due to their hard-work and due to the club and the players they're around with.
Read the post again Nobody was saying that they were cheap signings or wing it signings, but they weren't Mbappe type of signings, and there are only 2 clubs maybe 3 that can pay 200 million for an Mbappe type of player [Real,PSG,not even Barca can do that presently or United]. Go back and see what people thought about us signing Salah and Mane [I was one of the few that though that both would excel here] and Firmino. They weren't Mbappe level's of talent.
There aren't any clubs in the world that have 22 world class players in each position. There are teams that are close to that, but they have parts of their team if they are injuries or suspensions they will feel the difference. We are talking about 2,3 clubs at the very most in world football. City have quality in depth in midfield and in the attacking third, but their defending not so much, but even they can't afford to have world class defenders sitting on the bench.
In other words, I am not sure what your point is.