Uninstalling the Instagram app does not prevent me from still using it. I'll browse the web version on my computer.

And site blockers are not sufficient in blocking time-wasting sites. I'll open them in another browser (or just turn it off).

I found a new solution, blocking websites from through my hosts file.

You can do this with some leet hacker skills (not really), here's the steps.

It's annoying and tedious to do, but that's the point. If I need to undo it, I can, but the inconvenience is enough to stop me most times.

You can also do this on your iPhone.