There are very, very few breaking changes within Python 3. If you're an individual user, then upgrading to the latest version is almost certainly a good idea.

But there are lots of companies that release software using Python. To ensure a stable production environment, they upgrade more slowly, or on a schedule that's distinct from the Python release cycle.

Also, companies often don't just let people upgrade things themselves. The IT department schedules a company-wide Python upgrade, for example, testing the effects beforehand. I have several training clients still using 3.7 and 3.8, not because things would break with 3.10, but because they haven't fully vetted the newest version, and they're being super conservative.

I do wonder if companies will be a bit faster to upgrade over the coming years, given that execution speed is expected to improve rather dramatically. Upgrading won't be a matter of some nice-to-have features, but rather of real savings in system usage.