The upside is that the professional scene actually lives here. Rajadamnern and Lumpinee are in the city, the fighters you train alongside are competing, and the coaching is not shaped around holiday traffic.
The friction is logistical. You are commuting across a large city in heat and traffic to reach a session, which is a real cost in energy that camp accommodation elsewhere removes entirely.
For a beginner who wants the sport rather than the trip, it is a fair trade. For a beginner who wants a straightforward two weeks, it is more work than it needs to be.