Why in this sentence “too much” is not accepted as translation for “muito”, when in other similar instances what gets rejected is the simple “much”. I feel like I am missing something here and I would appreciate some background to help us decide whether “muito” means “much” or “too much” based on context.
Because that has a different meaning. See:
Your sentence means that you have travelled through Asia many times.
Duo's sentence means that you stayed in Asia for a long time: it could have been many travels (as you said), but it could have been just one single loooong trip.