Why, indeed. At this point it's easy to set up a home studio that beats any pro studio of 1970. The only catch is that the pro studios of today have grown too. We used to mix films from 8-track to mono, and now you go from hundreds of tracks to 5, 6 or more of surround!

We used to spend half a day mixing a 10-minute cartoon, now it takes a week.

Bah, humbug! It's all Parkinson's Law, as far as I'm concerned.

The chief difficulties are soundproofing & sound baffling, and a good mike.   After that, your own skill and experience.