The fact of the matter is that this is a min/max based discussion.
Maybe the best sentinel can outclear stuff like elec or sonic blasters, due to how generally terrible those sets are, but the fact of the matter is any top tier or even middling blaster will stomp the clear speeds of a sentinel.
Low target caps, weaker base damage and far less potential with a broken inherent is all sentinel has going for it. It's the poor man's soldier of arachnos. If a blaster manages to solve their defensive woes, it's no contest.
This isn't pre-i24 anymore, blasters aren't floor magnets. Their time spend eating dirt for so long has allowed them to siphon power from the well of the furies with their mouths, making them literal gods if built well.
Take it from a kheld main, though. Nothing in this game is useless, if you put time into your character, there's very few things in the game that can't accomplish impressive feats.
When weighing potential however, implying sentinels can even touch blasters is either ignorant or dishonest.