Sounds like you've never been to a true club fitting. They're done outdoors by a person qualified to assess your swing and make recommendations that you can immediately experience and decide what works best for your expectations. Your assessment of the big box stores and indoor fittings is is correct. There may be a few who know what they are doing, but very few.

Other than disagreeing that fittings are overrated, you are spot on about getting fitted in an indoor fitting station, not all fitters are equal, and retail outlets have on occasion, had questionable motivations. How do you know if one vendor offers an incentive to promote their products?
What I can say is I am the wrong expert to take advice on the best product for me. I am almost always wrong. In part because I am LH and old, there isn’t a stock set available for me for any club for me to assess is it the best for me. Part of my loyalty to Titleist products is they have enough n/c shafts to fit me to. The drive this year with the Titleist fitters focused on keeping the 5 mph ball speed for simplicity is so obvious yet so novel to implement. Titleist went to great effort this release to promote the T series irons as interchangeable to easily mix sets to the benefit of the individual, rather promoting the T350 as only the game improvement club and the T150 as only the better players club.

Your personal assessment may be accurate for you, but still a minority position.

I must partially agree and disagree. Agree that fitters are like any profession and there are good and not so good. Agree that indoor fittings are not the same as hitting outdoors. Agree that some stores will push you to a specific brand to get higher commissions. Disagree that getting a fitting is not important. Doing an outdoor fitting with the combination of TrackMan data and real visual feedback on turf and open range will take all the guess work out of the equation. Without it, you are making a purchase in the hope that you guessed right and are willing to risk getting something not ideal and then doing your best to alter your swing to make it work.

To add to the discussion, I have become more of a believer in fittings in the past decade or so. Having been playing since I was 7 (ok... going to age myself, but that was 45 years ago), back in the day, your choices for irons and metals/woods was pretty limited unless you were a pro. True Temper S300 was about it if you wanted steel, stiff shafts!! ;-)

Now, you can get an appointment with a qualified Titleist fitter, on a grass, outdoor range, and spend 60+ minutes hitting "real" (not range) balls (ProV1, X, etc.), with a TrackMan to get all your stats. They can go through dozens of different heads, shafts, lofts, lies, etc. to give you very accurate data and suggestions. Then it boils down to their suggestions, and your personal preferences to the look and feel of a club.

I know this is a Titleist forum, so some bias, but Taylor Made, PXG, png, etc., and agnostic fitters (Golftec, Club Champion, etc.) offer very similar services. I do think Titleist, with a reputation as a "players" equipment provider takes things more seriously then their competition when it comes to fittings.

The $100 fitting fee is money well spent if you get new clubs or not.