Many TV's that "market" the fact they are 100hz+ panels usually aren't true 100hz+ panels, but instead use frame interpolation to "fake" it.
Some TV's are 50hz, some Consoles will output to 50Hz, which would fit perfectly with games that are running v-sync @ 50fps as well.
But the main reason why games aren't locked to 48/50fps is because it's not an easily divisible number to 60hz, so you end up with screen tear... Where-as something like 30fps can just have a frame be displayed twice as long as 60 which is generally a smooth translation.
--::{PC Gaming Master Race}::--