It depends on what you consider difficult, I suppose. But also, it's a question of degrees. Say a group of 5 equally skilled and geared players (You know, that always happens XD) all with the Venthyr Covenant, defeat a +10 in 28 minutes, on a 40 minute timer. Same group, no one has the TP, and they clear it in 32-33 minutes. Not really much difference.
But I get it-in cases where not skipping a trash pack every minute would mean missing the timer, it's a valuable asset. But it isn't the communities fault if groups can't clear up to +15 without it.
But as to why would people do something, it depends on what they get out of it. It's faster to change lug nuts with an impact wrench, but changing a tire isn't a leisurely activity that you do in your spare time for personal satisfaction. Well, I mean most people, if it tickles your fancy, go for it
And in this example, if someone really wants to not play Venthyr, that is the tradeoff.