Assuming at least some of large UMD skill tome, exceptional bonus/green steel, stat tomes, past lives, litany, completionist, good gear... then sure. I have no trouble with UMD on my main, either, regardless of build (so long as I spend max points in UMD, and swap gear - and even spending points is optional if I only care about Epics).
But now try that Cha-dumped Barb with a new first lifer, where you will only get to no fail on a Heal scroll at cap, that's including good easily farmable items (+5 UMD, +11 Cha and +3 Insighful Cha), ship buffs, GH, and standard good luck item - as a point of reference, that's something I can have at around level 13 on my main given the exact same build.
Remember: not everyone plays decked out triple completionists, and for those that don't, +5 is a massive boost (let alone +10).