Speaking specifically about royals, until there is actual evidence to back one method vs another, I'll try to remain neutral and openminded. There are many who use racks because they genuinely believe their snakes are healthier(easier to keep sanitary) and happier(agoraphobic argument is the most common) as a result. While I'm not opposed to either housing choice, I never really understood the holier than thou attitude of people keeping snakes in a 48 inch enclosure versus a 33 inch tub. Some of the natural setups are undeniably beautiful, yes, but what benefit is that for the snake? Neither are anywhere close a wild setting, specifically in regards to spatial limitations, so who can really argue that the royal is better off in one vs the other? How are you measuring the happiness and wellbeing of the snake besides superimposing your own feelings over them?