the response rate for most monitors is ~5ms and the refresh rate is ~60Hz.
meaning, every time a video card changes a pixel from grey to white, it takes 5ms (5/1000 of a second) to change the monitor pixels; meaning the maximum frame changes per second is somewhere around 200, or a 200FPS cap for most monitors. 1ms response time monitors would have a maximum of somewhere around 1000 FPS.
that being said, you would need a 60ms response time to have a cap of 60FPS.
as for 60Hz monitors, color to color transition takes about 16ms, which makes for a 62.5FPS color change max.
so they're correct for people running 60Hz monitors, though FPS is usually measured by the amount of frames per second the GPU is running at, so the refresh rate of the monitor makes no difference. the monitor is running at ~60FPS constantly because of the 60Hz maximum, however there are monitors that run at higher Hz, such as 75Hz and 120Hz monitors. these monitors can run, respectively, ~75FPS and ~120FPS.
afaik the engine Roblox runs does have a 60FPS video card max because of some v-sync thing