But, is it though? Is eight years (or even ten) a good solid shelf life?
Yes.
If you look at other hobbies, things that are replaced every ten years aren't really considered to have a great shelf life. Boardgames to revamp their rules every ten years, at least, not the popular ones.
First, so what?
Why are you implying that board games are in any way relevant? I like board games, though I am definitely not a board game gamer. I own quite a few and the reality is that my copy of 7 Wonders has been played twice, Elritch Horror a handful of times, etc....
But they are not the same. The experience is not the same and my expectations is not the same.
Saying that RPGs should have the same shelf life as board games is, to me, akin to saying that comic books should be published as often as novels. Do we really need another Batman story when Gandalf is still doing well after all these years?
Even at ten years, we're still talking about spending about 20% of the lifespan of an edition building the next edition. It generally takes two or three years to produce a new edition. So, we're talking about hundreds of thousands of dollars, if not millions of dollars, being sunk every ten years to come out with the next edition.
Is it worth it? I don't know. I honestly have no idea. But, I'd be a lot more comfortable if we had twenty year gaps between editions. That we could have a stable game for a couple of decades before getting a new one.
What percentage of board games are still in print 10 years later?
Who many versions of Monopoly exist? How many versions of clue?
You mentioned Settlers of Catan upthread and I was going to tease you with a question about your acceptance of Star Trek 5E. I look on amazon and see that I can buy Settlers of Catan, 4th edition. That is an edition every 5 years. (and we already established that any change is seen by some as a reboot)
Plus
the 5-6 player "expansion"
Rivals of Catan
Catan: seafarers
Cities and Knights
Traders and Barbarians
Explorers and Pirates
Junior
(and Star Trek)
How many versions of Ticket to Ride exist?
What game both continues to exist in print with steady sales, for 10+ years, and has ZERO revisions and ZERO expansions or alternative versions?