This is generally true

but CZ has known about these issues for years and chose to do nothing when it would be a pretty easy process to improve. They know most people don't have borescopes and many of us would not call them on the advertised 1MOA or better accuracy.
Spare parts are out of stock everywhere. Even in the Czech republic. If the bolt handle breaks (like there are many reports of), it is considered user error and there's no recourse.
Fortunately my CZ457 is ok. Doesn't do 1MOA even at 50y though (I tried 30 kinds of ammo). It does do 2MOA at 100y with the right ammo. Which is ok for me.
My 21 years old Savage MK2 shoots way better.
My 2 cents...
IMO, CZ, like other manufacturers are becoming more of a marketing concern than a rifle maker (Savage has got so many models, same with the Ruger 10/22 until recently... they actually made some meaningful design changes with model reductions recently). Their designers are great at coming up with very marketable designs and features that people will buy; and I believe, not paying as much attention to process engineering issues. Regarding fit and finish, I have owned a lot of CZs over the years; the 452 is the epitomy of fit, finish, art and ballance in their time when it came to an "every one's" rifle. There were a hand full of models that catered to specific needs. The 455 was introduced with more models and stock configurations and the changeable barrel. Still nicely machined with good fit and finish, but they dropped the recoil lug, no pillars in the stock, but very loose holes for the action screws. Now, before thinking "you don't need a recoil lug in a .22!", there were quite a number of these rifles got bumped on the but-stock, and cracked, or sheared a big flake of wood from behind the tang of the action. I got a nice 455 action to coustomize at a reasonable price because the CZ Super Match got bumped and the stock broke. CZ noticed this issue and the 457 now has a chincy plastic recoil lug; some models have plastic bolt shrouds. Retooling costs a lot, retooling every years for model changes and feature additons cost money. CZ used to build a few models to a quality point, now the build a lot of models to a price point. Price increases have outstripped our rate of inflation.
I'm not saying that I will never own a 457, but I don't see a need presently. Frends let me shoot theirs; the reduced bolt travel opening and closing and the recoil lug are improvements; fit and finish is not, the side safety may be seen as an improvment; for me, the old bolt safety is instinctive, so no advantage. It seems that lots of people are changing the new-improved adjustable trigger with after market triggers, or buying spring kits to improve them. So, no big improvement either.
In the 2010's everyone and their dog was customizing a Ruger 10/22, today, it is CZ. Lots of 3rd party companies supplying stocks, chassis, barrels, triggers, knobs, bells and whistles.
Tika and Anschutz seem to not have followed that trend. Tika has way less models. Anschutz has had less regard to price point and more concern about quality.
If someone is planing to customize, I would suggest following the route I did and pick up a reasonably priced used 455 that will likely already shoot very will, and will develop over time.
Here is a photo of mine old 455 now:
