It’s bloat. You don’t need a client to create events and can imitate a client anyway. You know the poster pubkey, time of creation - what more do you need to follow up if critical?

Plus adding it means lazier coding as expecting a client (which will happen), means less exception or validation handling - and less robust implementations. Expect anything, never trust user input, validate everything.

Browser user agents are completely bull crap today - Apple iOS messages pretends it’s Facebook for previews, everything has WebKit/gecko, it’s just all incorrect bloat from a legacy time.

Optionally while testing is different and no real problem.