I believe this is painting with a very broad brush.
I bought an iron sighted G19 Gen 5 in 2017 when they first came out. Racked up 6,709 rounds over 3+ years. I picked up a Glock 34 for USPSA and put an optic on it, a Holosun 507c. So I'm pretty familiar with Glocks, having owned two G19s, a 34, 43X, 48 and a 26.
I tricked my G34 out quite a bit; Apex connector and trigger, polish, etc. Best score I shot on The Test (10 rounds in 10 seconds at 10 yards, scored on a B-8 out of 100) with it was 97-5X.
After I bought my P365X, I put a Holosun 407k on it and repeated The Test. Best score with the Sig was 97-3X.
I don't consider myself to be a particularly good shooter, but I just didn't perceive any significant drop off in performance, at all. My personal opinion is that these small guns can be shot well, or very close to as well as makes no real difference, if you put a little effort in.
Now, if you have L or XL hands, this may not apply. I have M/L hands, but despite this, I still have to work on a good master grip on the draw, and constantly be vigilant about support hand, otherwise I tend to shoot low and and away. If you have L or XL hands, you're going to have problems with the small grip size of a P365, say. The ROI for that small reduction in performance is a huge increase in concealability, at least for me.
Of course that's why suits vary in size from a 36 short to a 42 regular to a 48XL, people are different sizes. To state categorically that small guns can't be shot well is a bit off the mark *rimshot*, in my humble opinion.