But its not. Its not healthy squad management to have every player in more or less one age bracket. Its going to lead to problems long-term and you will have major issues with giving a lot of young players the minutes that they need.
This idea that we would be "sorted for years" is naive for the same exact reason. Next summer there will be a new Haaland, Dembele or Joao Felix available which the Caf will scream for. And the year after and so on.
Also: the jury is pretty much out on Haaland until he performs over time in a bigger league. Fred was awesome in the CL as well, but played in a league of the similar quality as the Austrian.
I wont be upset if he comes and would welcome him, but I surely would prefer the investment be made elsewhere first and foremost.
If we do need a striker (I dont think so) I would go for an older one that wont hamper Greenwoods progress for example. And keep the squad age healthy attacking-wise.
There will be a new Haaland in a year or two.
If Mbappe wanted to join, I would not mind, but that would be the exception to the rule. But he is a generational talent.