Board Thread:Naruto Discussions/@comment-294840-20170617145112/@comment-734582-20170621172636

Starscream1998 wrote: Honestly nowadays you get characters growing eyes out of their hands and all over the place, long gone are the days where in Naruto these mystical eye powers were legendary before Madara came and just started playing Mr Potato head with Sharingans and Rinnegans. Madara's Rinnegan got tossed around a bit, but until the latest stages of Naruto (where Sasuke got one) there were only two in existence.

In Boruto the Movie, Momoshiki eventually has three. If you count Hagoromo's manifested spirit, the biggest amount of Rinnegan in existence at any time was 5 (Hagoromo 2, Madara 2, Sasuke 1 or Sasuke 1 + Momoshiki 3). There was only ever one Rinne Sharingan (Madara manifested Kaguya's) and there was only ever one Wood Release (hashirama's).

It looks far worse than it really is. Sharingan was rare in the start because the entire clan with that KKG got wiped out alá Shikotsumyaku/Kimimaro