It wouldn’t be onerous…in fact the majority want something like that…but that’s not what’s being discussed as opt-out (except by @soundofthunder). That would be opt-in.
The opt-out version is enabled by default.
With opt-out, that data is sent until you turn it off. The only way to stop it being sent at all is to prevent internet access until you’ve disabled it.
EDIT:
If you don’t believe me then read the options for the vote and these two posts (which are what prompted the discussion of opt-out vs opt-in and this vote):
Testers needed: Manjaro Data Donor
Testers needed: Manjaro Data Donor - #146 by romangg