This is explained in the article:

> The new CPU family marks one of the largest architectural jumps we’ve had in years, as the company is now baselining all three new CPU IPs on Armv9.0.

I believe the deprecation of AArch32 is quite an important change and by itself already warrants issuing a new major version (then there's all mandatory extensions from v8.2+ and SVE2).

They have not claimed to bump the major version on a regular basis from now as you seem to suggest.