Nobody is forced to hand them any data. If you do it anyway, it is not their fault.
My friends and family use GMail, meaning I can't communicate with them without sending Google all that data.
It's your decision - you could say you blocked Gmail. Admittedly, that wouldn't be nice.
Similar to messengers: I am not reachable over WhatsApp, although my family only has that...
I'm not going to shut out my grandparents because they use GMail, and I'm not going to try to convince them to switch off GMail after already being a jerk about not having a Facebook account.
Besides, GMail's limited algorithmic sorting is pretty innocuous; it's Search and Facebook, with their pervasive filter bubbling, that're actually being a problem.
As for messengers... I've never had a problem convincing people to SMS me.
Yeah it's tough. It's the same reason I still use Facebook: Without it, I would be cut off from a large number of family members that only use FB and don't communicate in other means.
That is their choice disrespecting yours one though.
Some objections to your statement:
It's difficult or impossible to know what data you're "handing" them.
Even if you try to stop handing them data they still collect it. See: google collecting location data.
They use fingerprinting techniques to track you even though you aren't logging in or submitting any data to them. Nowhere in that scenario are you handing them data, they are harvesting it.
But yes, on the face of it if someone clicks "I agree that you collect data" they're on their own. But reality is more complex than you let on.
I use LineageOS on my phone, duckduckgo search engine, maps.me geolocation and my own local mail service, etc.
For those who care about the privacy and understand that G should GTFO, it is extremely easy.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.