Those comments are true for any Powder developer, like ID-11, D76, Microdol-X, Perceptol etc.
If you're referring to my comments, that's partially true;
except that most developers
do discolor when they get old and die; XTOL doesn't (usually). That's critically important. Suppose for the sake of argument that there's a pinhole in the cap of your storage bottle. If it's got D-76 in it, the developer will turn brown and you'll know there's something wrong, so you won't use it. If the bottle's got XTOL in it, it won't turn brown and so you'll have no clue it's gone bad. Is the failure XTOL's fault? No, not really; but the fact that the developer didn't "warn" you of its impending failure
is XTOL's fault, in the sense that most other developers do provide such warnings.
Also, it's my understanding that ascorbate developers, such as XTOL, are more sensitive to contamination from certain metals than are MQ developers such as D-76. Certainly Ryuji Suzuki makes a big deal about such contamination in his discussions about XTOL and his DS-10 formula. To be sure, any developer can be ruined by contaminants if the water's really bad, but my impression (admittedly speaking as a non-chemist) is that ascorbate developers are more sensitive to this issue than are others. This is the basis of the recommendation that's been repeated here by several people to use distilled water when mixing XTOL.
Also, let me just point out that we're all really just blowing hot air. I have yet to see hard data on XTOL failure. Anecdotal reports of failure rates (both good and bad) are pretty close to useless. There have certainly been reports of XTOL failure, and I have no reason to doubt the veracity of these reports; but we don't know their frequency -- 1 in 10, 1 in 1,000, 1 in 1,000,000, etc.; and we don't know how these rates compare to failure rates of D-76 or other developers. The main causes for concern are in the number of anecdotal reports of problems (which suggests, but doesn't prove, a higher failure rate than exists with most other developers) and in repeatable observations (of XTOL's lack of discoloration when it goes bad, for instance).
One more point: A reduction in the frequency of XTOL failure reports over time doesn't necessarily mean that a problem had existed but has been eliminated; this could just be a reflection of the decline of traditional film photography generally, or it could be that the problems were/are related to things like specific (and rare) water-quality issues, and those with these problems have stopped using XTOL as a result.
Finally, let me say that I'm not trying to beat up on XTOL or advise against its use. I'm just concerned that the "it worked for me, so it must be fine" comments might lead potential XTOL users to treat it just like they would D-76. XTOL is not D-76, though. IMHO, one should be more careful about the mixing and storage of XTOL.