Everyone hates Tapu Tapu so blame it for everything... Sure.
bobharlem has it correct, slides not getting people through is only an issue if people aren't in the line. When I went, I had to wait no less than 10 minutes for every slide, even with Tapu Tapu returns.
"People are in the park instead of lines, thus lowering capacity" doesn't make sense for several reasons as well. 1) That was the entire point of Tapu Tapu. They planned for this. So their capacity planners should be fired if this is the case. (Eg, this is just plain stupid iftif t is true.)
2) They can always adjust the Tapu Tapu times to increase the number of people standing in lines. Just reduce it from 90 minutes to 60 and boom, you have 30 minutes of people in a line. Then there's no need to get rid of Tapu Tapu, since it still has the spirit in tact (saves 60 minutes off 90 minute wait).
I personally love the Tapu Tapu idea and hope it succeeds. As an avid theme park visitor for decades, the worst part of any visit *by far* are the lines, so any attempt to solve this great in my book.