I actually agree and disagree with your arguments only based on the examples you’ve shown. Two of those examples were product websites where there is more than one main task to complete based on the context, and we are ignoring the on boarding fact. The support icon there, in both cases, is to be easy to access. The location of it has to do with the fact that our peripheral vision is better than our frontal vision. Most of those icons only show after a certain amount of time or animates after a certain amount of time. As good customer experience (this might not be the best user experience) the product only gains by helping users with specific problems while using the app.
I agree with you when I see this same UI pattern being used for something unrelated with customer support like newsletter signups, or marketing blobs.
The fact that google material design uses this UI pattern for the main task on their apps it doesn’t mean it can’t be used on other contexts where it makes sense.