Re: Wonder why Netflix doesn't have this
It's not supposed to show you things similar to what you watched. It's supposed to show you things you might like based on what you watched (it assumes you liked the things you watched).
Netflix have invested millions into this algorithm - they ran a contest for programmers to tune it years back.
Have you tried watching suggestions? If you do, you should rate them and it will get better.
I have often been put off shows recommended, only to find they ARE exactly something I'd like.