Is washing your hands before eating being a "germophobe" or is it basic hygiene? How far back do we go in order to improve our immune system? Do we stop washing our hands ever? Do we stop washing taking showers?

There's obviously a balance with the best outcome. I doubt washing your hands before eating will make your immune system any worse.

You don't need to be a germophobe if you just care for basic and decent hygiene.

And I really experience a lot of people just not caring for basic hygiene at all when outside.

There is also a whole host of mental illness that are triggered by physical immune responses. Eating disorders that stem from one bad diarrhea episode are a really common example of this. Both ends of this spectrum can result in bad mental health.

Both ends of this spectrum can also result in physicals health issues too. Get a stomach bug and end up with post-infections IBS. On the other hand, stress from fear of germs could also cause IBS. Sadly you end up with the same result. Both approaches, when taken to the extreme, can cause equal amounts of health issues.