tl:dr of the following: I think snow conditions make a big difference in how noticeable a "worn-out" ski is.
As another anecdotal data point, I have a pair of Fischer FIS SL skis that at this point I can't get to turn worth a damn. If I didn't trust the guy who ground and tuned them (who is both a coach and has done several pairs of skis for me), I'd say there was something wrong with the tune. I mean, it's not impossible he just goofed, but I can't identify any issues with a true bar, and I strongly suspect the sheer number of days on the skis is more of an issue.
I got the skis in 2007 and they were my primary coaching ski for seven years after that; I'm primarily a weekend coach, and during a couple of those years, I was only helping out from time to time, so I'm not sure what the total day count would work out to—probably averaging 35-45 days a year on those skis after figuring in all-mountain-ski days and GS-ski days, but also a lot of time on the side of the hill. They remained my primary slalom ski when I then moved out to Montana, although I took a year off from coaching and did very little skiing after breaking my leg in December. The next four years I was on the hill at least two, if not three, days each week, and often on those skis, without any significant issue. They still have visible camber.
I moved back East in 2018, and from the first day I was on snow here, I was hating the damn things. I'm convinced that something in the internal structure of the ski isn't as it once was, and the firmer snow here makes it much more evident. At this point, they're a dedicated "side of the hill and slipping" ski, largely to avoid a whole bunch of t-bar laps on other skis. that I'm trying to keep wax on, and the best I can do is either sideslip or sorta fake turns.