Is it? On Linux, you can overwrite the file, but the underlying inode will still be open, and the 'invisble' old version will linger around - you don't have any easy way short of restarting everything to make sure the new versions are being used.

And with Chromium this directly leads to crashes - when you update the browser as its open, the new tabs will open with the new version of the binary, with the old ones still using the old binary - which usually leads to crash.

I prefer 'you cannot do X' instead of 'we allow you to do it, but it might misbehave in unpredictable ways'.