Industries get killed because they offer a better business model. Uber killed the taxi industry because they have a better customer focused business model.
SPAs run a better customer focused business model. So SPAs will always survive.
Not all girls are equipped to coordinate all the back office aspects of becoming independent. Booking rooms marketing, collecting fees , changing hotels , being in hotel room alone etc. Negotiating prices.
Just like everyone is not equipped to becoming a Entrepreneur, some people just want to show up for work and leave when there shifts over.