The game is actually easier if you do the Roya lewd stuff; you get all kinds of items, money, quest progress etc whereas pure Aura often has to pay or do things the hard way. The only big downside to playing lewd is it gives you more Corruption, which can lead to a game over if you don't have mental changes to spend it on. On the other hand with all the extra money you have, you can be stronger overall and have to use Star Knightess less often.
I haven't read the guides and I'm not sure why the lewd one would have you avoid doing lewd stuff, though my guess is it's trying to line them up for maximum lewdness increase (you want to do the less lewd ones first, and always do them at 0 effective willpower for lewd stat increases. If you did it right, you will see pink text from Aura.)