And for good reason - logic is scant on public forums.
What question marks are those? The defence is as good as any in Europe. By the end of the week the midfield will be as well. An attack of Jackson, Broja, Nkunku, Sterling, Mudryk, Madueke, Olise, is hardly terrible.
Your argument disregards the state the club were in at the time of purchase - horribly unbalanced squad with a massive wage bill and a terrible recruitment setup. You also skip context of a 1bn spending spree as if it was all spent on ready-made players for the first team. For starters about a 5th of that was spent on loan/multiclub prospects. Should be 500m in sales over 3 windows as well. As I've said before, you don't sell Hazard for 100m, replace him with Antony for 100m and then claim the club should be a better position because 100m was spent.
Seriously?
If you look at the squad position by position, and then ask yourself this question: If you imagine a Chelsea team that has evolved to the point where they're seriously contending for the PL title, has this player shown that he's good enough to be on that team, or has he shown the opposite, or is it just too early to tell?
If you do that, I think the only part of the team where you get a clear thumbs-up is the wing backs. As for the others;
Goal: Is Sanchez or Kepa who you see playing in goal if you're challenging for the PL title? Good keepers both and it can't be ruled out, but I'd be surprised if Chelsea weren't looking into the possibility of an upgrade at some point on that path.
CBs: Thiago is obviously proven, but can't last much longer. Fofana is on his third straight seriously injury-ridden season. Disasi, Colwill and Badiashile
could well be an elite central defence in a year or two, but no one can reasonably argue they've proven they're that level yet - certainly not as a unit.
Central midfield: You could argue Fernandez has already proven he's a genuine linchpin for a top team, although you could also argue it's premature to say that. Caicedo and Lavia obviously warrant big optimism (as does Chukwuemeka), but still, they need to show it for a protracted period before you can say there aren't serious question marks.
An attack of Jackson, Broja, Nkunku, Sterling, Mudryk, Madueke, Olise is hardly terrible no, but it also hasn't shown yet that it's adequate or good, and these are not players of such astounding quality that it would be against all reasonable expectation should they fail to deliver. A good few of them did just that last season. Every single one of them goes in the "too early to tell" bag.
in short - this is a squad brim-full of "maybe he will, maybe he won't" players. In part that's simply because so many of them are new, but that also means you reasonably have to accept there's a greater level of uncertainty here, as opposed to just assuming that just because these are good players with obvious top level potential, that's what they'll be. If you think stuff like you've got a defence "as good as any in Europe", you're taking a lot of things for granted that you can't possibly know yet.