Throwout bearing has nothing to do with engagement or disengagement of the clutch (meaning a good one or bad one will not matter). As long as you have one in reasonalable condition, you will disengage and engage the clutch the same way. If a throwout bearing is bad it will make whirring sounds, vibration or rattling when the clutch pedal is pressed. Definetly won't be smooth and quiet, but the clutch will engage and disengage. All it does is act as the end of your hydraulic ram to press into the pressure plate.

If you are having problems engaging/disengaging/ plus clutch slippage I would think about things like

-hydraulic system bleed out air bubbles
-dirt/mud/water on input shaft, in bellhsousing, in between p.p. and flywheel and clutch disc
-surfaces no longer greased due to water and dirt, splines not smooth
-burned/glazed/contaminated disc or flywheel

also rare things like:
pilot bushing worn out (causes wobbly input shaft)
bent or damaged input shaft or input shaft splines
damaged pressure plate fingers

this is just a partial list of course.

Also bad rear main seal can add oil to the mix making this even more fun.

How is your distributor o-ring? (big source of oil leaks that can affect clutch performance.)

If your clutch is quiet when you press the pedal my guess is your Throwout bearing is OK