There is a difference between switching protocol, and:

  - not migrating to broadband from 56k modem
  - not upgrading to a browser version which supports HSTS
  - not trying anything with new features at all

HTTP/1.1 still serves its purpose, successfully, without any impact on performance/usability. I'm not Google, I'm not serving a webpage to 8 billions devices at the same time.

Sure I can try HTTP/2 (and I did), and HTTP/3 (and I will). But when it comes to distributing an application/service to customers, I'll automatically choose the battle-tested 30 years old technology which is supported by everyone and every device.