I see what you're saying but without Conte being able to stand on the players necks, (due to the aforementioned problems) and the injuries and subsequent loss of form to some who also regressed in mentality to some extent (which was his main point from his rant I think), we weren't able to improve our performances. At one time we had every forward player injured at the same time bar Kane - where's the creativity coming from?
The football wasn't pretty but give Ange the same players Conte had and he won't do any better in the league, I actually think we'd be lower than 4th. Conte played a pragmatic defence first system designed to protect the goal. We were poor defensively and lacking creativity so he played a system to maximize our strengths, mitigate our weaknesses and when he was fit, firing and focussed it worked.
This continued into last season when we had 23 points from the first 10 games before everything went wrong (death, injuries, illness).
Regarding Milan, yes they sussed us out by playing an equally pragmatic game that hinged on key moments, but outside of Kane, Son was woeful as was Kulu and the supporting cast weren't good enough or injured (Richy, Dan, Lucas). And Milan turned over a rampant Napoli next round which suggests they weren't as bad as many suggested.
The improvements planned for the squad now are vital because without them we're going backwards. Managers don't mold players from average to good, their technical ability, speed and intelligence are fixed by the time they are in their late teens - all they try and do is improve confidence, mentality and tactical awareness.
Ultimately we need better players - every player we had in the peak Poch era was better than what we had last season (bar the few who are the same). That's been our biggest problem since 2017 and until we address it, results generally won't change.