Not clicking the link, but just from the summary, I can already see that the author is attributing it to the wrong problem.
The issue is that ongoing support of old games, in GTA's case, GTA Online, has a way of consuming a large amount of company resources. So long as a monolithic ongoing project remains profitable, the company behind it has little incentive to make anything new.
Look at Epic. When do I expect the next big game from them?
...About the time that Fortnite stops making a massive profit.
Of course, the consequences of betting big on an ongoing game can backfire. Look at Concord, and, well, Sony basically declaring that their entire release slate was "Live Service" stuff. Sony may have pivoted away from that, but there's no question that the PS5 library has been slim, and a lot of it was due to resources being poured into live service stuff.
Not saying GTA 6 isn't big, and almost definitely too big, but GTA's own success is kind of to blame.
...I've been feeling that this was a problem since the Ultima Online days. There were other factors, but UO's success had a large part in the franchise ending, and a lot of other studios have followed a similar route in the years since.
But also... why, really, does AAA really matter? The gameplay isn't necessarily better than anything out of the smaller studios, so what we're really paying for is graphics that requires hardware that costs too much with dev cycles that take too long.