Discussing McDonald’s in the context of late-night dining in SD is neither an indictment nor an indication (qualitative, quantitative, or both) of the city’s late-night dining scene. McDonald’s is an option for post-10 p.m. dining in SD, among many others.
Discussing it just means McDonald’s is popular, which is probably true of McDonald’s in many cities across America, regardless of the time of day (or night).
It’s not a problem at all.
In most major metropolitan areas, SD and LA being no exception.
There are many fine dining options in LA past midnight. Just because you don’t know where they are, doesn’t mean they aren’t extant, or otherwise limited in some sort of self-imposed artificial manner.