This is valid but in both directions: people will say "Firefox is slow" because they don't have the time/interest to say "Firefox is slow on this specific webap

This is valid but in both directions: people will say "Firefox is slow" because they don't have the time/interest to say "Firefox is slow on this specific webapp that is very important to me on my specific laptop". Of course the responses to the first statement are going to interpret it generally rather than specifically.