1. Gameplay
Although I love having all my eggs in one basket, it'll make sense that you can't have it all at once. This creates a challenge as well as it also increases your replay value.
For pure gameplay, this might be useful, sure. But it will always feel arbitrary to me.
2. Real life experience
You asked why one thing excludes another. Well, specailised commercials and universities don't cancel out each other, but can you really imagine a romantic trip into nature when a huge industrial zone dominates the horizon? I think, we've got something here, it just needed to be fleshed out a bit more.
Tourism comes in many forms - but yes, having a natural park / wilderness type tourism area clashes with heavy industry. They should not exclude each other in the city, but definitely be kept separate. Wilderness would not fit with most land uses, however. You won't go camping next to office towers either.
Leisure tourism and cultural or event tourism don't care than much about industry, though. Again, the actual destination should not be inside the dirty industrial area, but otherwise, it is quite realistic. Pollution and pollution-like mechanics could help here, lowering the efficiency in ill-suited neighborhoods.
What about harmonizing factors? University and commercials can harmonize, industry and commercials can harmonize but low tech industry and university harmonize only for a short period of time, as students might need the quick money but afterwards, they refuse to stay at the assembly line for the rest of their life.
Not everyone in a CITY (not town) with a university will be educated at that level, even though a large university will attract other industries. CS is quite unrealistic here with the university sizes compared to the cities. Not every student would stay in the city, either. The other way round should be considered, though - high tech industry should struggle in cities without reasonable educational facilities. Low tech industries would
struggle in university cities due to being outcompeted by the high tech, to a degree. CS cities are large enough to accommodate both sections, however.
I'm not against the idea in principle, but it needs to be sensible. Real cities tend to be quite diversified places, not completely specialized at all. More nudging to one type or another is fine, but hard restrictions should not apply. Replayability could come from
optimization, not unlocking paths. It's not like cities get built in a day anyway, one city could be plenty for months.