Though what this essentially says is: summons are OP.
(I mean, once they're summoned, having them help out as opposed to making their own attacks isn't particularly OP.
At low levels, abstaining from their own attack is a significant cost. At high level, it isn't, but at that stage having the Summoner hide to avoid losing Concentration becomes a cost in itself. Plus, foes with area attacks that can clear out all summons on one swoop are no longer rare)
But yes, you're basically right: using your Familiar to gain advantage in combat is discussed much more often than the utility of the tactic really deserves. (Unless your DM is afraid to slay the familiar, of course)
I wouldn't say that summons are OP, but if used well, they can become very potent.
Just using them to attack is not always the best strategy. I have seen a line of them being used to split up a large group of monsters using the Dodge action. It takes a while for the foes to bust through that line and in the meantime, the PCs can focus fire.
I suspect that many players use them only to attack whereas the Help and Dodge actions can be used in special circumstances.