I don’t think getting freebies from them counts as supporting them

I do. Some examples off the top of my head:

• giving them access to your stored data, both through account creation and by letting their code execute on your computer
• giving them access to your system fingerprints, through the same
• giving them access to your behavioral data, through the same
• giving them legal influence over you, by agreeing to their terms
• giving their legal arguments greater weight by increasing their market share
• giving them greater sway with publishers by bolstering their user count

There are probably other ways in which it supports them. Those are just the first ones to come to mind.