WayneLigon
Adventurer
There's also another thing to consider - it's pretty obvious that the Jedi, by the time of the prequels, are not what they were. A lot of knowledge has been lost, and now, very possibly, Yoda is the last Jedi who remembers the old ways. Palpatine has also had decades to work his magic on them as well, a word here, a word there, to young Jedi who then rise in the ranks to the position of trainer or master, letting his subtle poison spread further until it's so ingrained that nobody even notices, not even Yoda until it's too late and you get that whole sequence where the masters finally realize that 'their ability to use the Force has been diminished'. It seems very likely that Palpatine has planted those seeds over a long period of time, to weaken them greatly before the final reveal.