but it can be really boring to watch two really good guys going at it once tired and waiting on the other guy to make a mistake so they can catch them. That's why I'd support the imposition of a stalling thing, or the pin thing, just to get the action going again.
That shouldn't be happening, referees should be telling the fighters 'work or I stand you up', too many refs aren't qualified and don't realise that they should stand them up if after being warned they still don't work. Judges should also realise that 'laying and praying' shouldn't attract points! There is a remedy for not working, it's just that officials don't seem to either know about them or don't care. Too often judges will 'mark up' a takedown but forget that unless followed by positive techniques then it shouldn't be marked up.
Rules from UFC Judging section
F "Effective grappling is judged by considering the amount of successful executions of a legal takedown and reversals. Examples of factors to consider are take downs from standing position to mount position, passing the guard to mount position, and bottom position fighters using an active threatening guard."