Are specialists necessary?

Wondering: Is it vital to see specialists (rheumatologists and ophthalmologists, etc)? Am I flirting with danger by staying with my PCP (an internist) and optometrist? I have not had the best of luck with specialists in the past and often there’s a long wait to see them. I am in a new community now and would like to keep things simple. Sticking with the internist and optometrist until I have reached their limits seems prudent. From what I read, we are often informing our doctors through our own experience and the anecdotal information gleaned on this site whether or not they are specialists.