It’s a big issue for most people. The goal is to try to do it as few as possible by using browser extensions, the new nsec bunker tool coming, or other methods.
Discussion
In my opinion it should be a big issue. I only use browser extension, which is easy for me because I don't use social media on mobile devices. The movement looks to be towards app based integration with nostr which will require disclosing private key to a third party. Correct me if I am wrong on that detail.