Activism like this isn't for people on Lemmy, who have already been exposed to the likes of decentralisation, open source Vs closed source etc.. its predominantly for those that still think brand name = quality.
I don't use social media these days, but i do have inactive accounts; I'm considering logging in and changing the pictures to clippy. It may have absolutely no effect, or it may be the 16th clippy PFP that someone sees, which may then prompt them to ask why everyone is changing their photo to clippy.
So whilst it won't change anything in a large way, it can act as the catalyst for those who are still unaware to try and educate themselves on the subject, and hopefully lead to them leaving Microsoft products altogether like you've alluded to.
For example; I'm already not using any Microsoft products, so continuing to not use their products is less impactful than by changing my mainstream photos to clippy, even if it has no effect.
We can try to tell people about the evils of microsoft until we're blue in the face... But if they "research" it themselves, it's far more likely to stick.
Damn you sir, you didn't need to call me out with that last paragraph.
No, I know it wasn't my shoe, but look at how well it fits!