>>14014687tl;dr: you're statistically much more likely to draw dragons and winds, anything other than a Pair of Not-your-wind prevents Pinfu
27*4 Tiles good for Pinfu, 7*4 tiles bad for Pinfu, now 8*4 Tiles are removed from the game.
I phrased it dumb, what I mean is not the calls rule making it harder but the overall amount of tiles existing in general.
I'll explain Pinfu anyways.
>Wait what? And what the fuck is a Pinfu and what isn't then?Pinfu's actual meaning is "a 0-fu hand"
now what the fuck is "Fu"?
Any classic Riichi Mahjong scoring Table has a Han and Fu graph. We all know Han, Red Dragon is one han, Chiitoi is two Han, Hon-Itsu closed is three etc.
Fu is the sub-scoring unit you only actually need in really tight games to make the right decisions, and you might as well disregard it in online play (I know I do). There is actually a formula behind Fu with which you can calculate hands, but since Japanese people are lazy shits any Hand over 5 Han is capped at 8000 (Mangan) and so forth.
You get Fu for most things which are not a sequence, i.e. triplets, as well as your Wait and how you got those Triplets (having the Kan by yourself vs. calling the Pon then drawing the last tile). I won't bore you with the exact table and it's on Wikipedia but Pinfu requires 0 additional points, and this is where wait comes into play:
Pinfu can not be declared if you wait on an 8 in 7-8-9, or a 3 in 1-2-3, it always has to be the plain double-wait of 4/7 on a 5-6 and similar waits. Triple-Waits count as two double waits and so on, it can NOT be a Tanki (single Wait).
And Pairs of Dragons also give Fu by themselves, so do prevailing Winds (Round-Winds) and your Seat-Wind.
Here's the even longer version:
https://en.wikipedia.org/wiki/Japanese_Mahjong_scoring_rules#Counting_fu 