Now I think you're just intentionally misinterpreting what others have said and what they meant by it.
Every Chelsea fan has been worried about Kante's injury record for the last few years and every Chelsea fan has recognized for a while that he's past his best. I mean, one would have to be pretty damn thick not to recognize it they had watched our games on a regular basis since Kante joined. However, none of that means he's still not been one of our best performers and one of our most important players when fit.
Going into the season even a Kante past his best was still a hell of a lot better than most, if not all, of the other midfielders we have but that's only because Kante's peak level was so absurdly good.
The fitness issue has been a growing problem for a couple of seasons at least, which coupled with Kante's age and contract situation has lead to people realizing we need to start thinking of a continuation plan for the future.
I'm pretty sure I speak for almost every Chelsea fan out there in the world when I say that within the boundaries of our current midfield composition (Jorginho, Kovacic, Kante, Gallagher, Loftus-Cheek, Zakaria) nobody in their right mind would reduce a fit Kante to be a squad player or a bench warmer. Any idea of selling him or reducing his role came with the built-in assumption that another high quality midfielder, only younger and fitter, would come in to replace him and not that we'd just keep relying on the others from the current bunch even more. Now that the continuation plan hasn't happened yet, Kante is by default still a very important player to us and one of the first names you'd want to put on the team sheet for an important game. Now whether that will still continue to be the case once he returns from his current 6 month injury lay off is anyone's guess but at least going into the current season he most certainly was.
Which brings me back to my earlier post about whether to extend Kante's deal or not. Assuming at least 2-3 players out of Jorginho/Zakaria/RLC/Gallagher will be gone by next season and a minimum couple of new high quality DM/CM are brought in to rebuild the midfield around, I'd happily still keep Kante as a luxury squad player to contribute whenever his fitness allows him to but if the idea is that by extending Kante we can postpone the rebuild and still rely on Kante being a key player for a couple more years then in that case I'd just pass on the extension and use his salary to get someone whose fitness is more reliable, even if their peak level wasn't that of current Kante's.