With so many interview preparation sites at our disposal, are they really helpful or are they making interviews really very tough.

I just got rejected from a company after a system design round where the interviewer expected me to answer almost in a similar way like the solution was given on g*** k*** g t** s***** i**v*.

How do I know that? He asked me the same questions/considerations/trade-offs which were given on the site for that design problem in the same sequence, many of which does not even make sense to be covered in a 40 minute interview.

So can I no longer get selected if I do not read the solutions on one site which is very popular these days.