Probably as much to do with industry/economics as anything. Bands like The Cure and the Fall were releasing an album (or more!) a year for their first decade, partly because it was commercially viable to do so. By the time the 90s arrived, 2 or 3 or 4 years between albums was much more the norm.
Assuming there’s a rough correlation between increased time to write & record and increased quality, and between higher quality and greater longevity, that is, which is not a given.
I dunno. Probably just making shit up.