All valuable and interesting viewpoints above. To answer your question the appeal was much more of a mutual experience and more cost effective than seeing an escort. I would pay anything between £200-£400 for 2-3 hours company for something that when it works/clicks felt like fucking a potential partner than an escort. Crucially it was always much more cost effective and gratifying than seeing an escort. I saw plenty of women who were in it just for the thrill, sex and cash.
That said there are pros and cons to every situation and currently I'm very happy seeing regular escorts who have dabbled with the seeking life as the maintaining of a SB relationship can be tiresome if you have a punting mindset which I do. Although I'm 100% transparent from the beginning about my needs and expectations - I'm sure many men promise the world, get the prize and disappear.
As for your question about the why not use the dating apps? I'm on tinder and have hooked up with a handful of ladies from there who are into sugar. The difference is it takes way more time as the majority of women are on there to find a partner not a sugar daddy, while Seeking used to be(I've not been on seeking for a year) much more targeted and easier to make plans.
This seems more logical, especially the first and last paragraphs which tend to get glossed over.
It does stand out to me that you mention dating apps take more time as the women are there to find a partner. That brings me back to my original thought that Seeking/SB sites are ultimately about a transaction between parties, which is the dividing line between them and dating apps. whether that qualifies as enough of a difference from SW i suppose is up to the individual.