Haven't heard it put that way but that's pretty much spot on.
I agree completely with you....there will always be groups that are offshoots from other religions, and they use what they want from the former religion, and adopt other things to add to their new religion....
Was Jim Jones a representative of whatever religion he was supposed to be?...of course not...was David Koresh, representative of whatever religion he was supposed to be?...of course, not...Does the Westboro church represent whatever religion they profess to be?...of course not...
And I could go on and on...I think everyone, with a tiny bit of actual thought, could get this...
There will always be evil folks who will use their evil ways, to distort whatever religion they profess to be...
My understanding has always been, that these splinter churches, who profess that they are LDS, and practice polygamy, are not considered to be LDS, by the main body of professing LDS believers...
However, if one is anxious for a fight, it is always handy and tricky, tho deceptive and lazy thinking, to trot out some splinter groups, and take their actions, to be representative of the larger group as a whole...
However, it is in the end, an ineffective tactic...this tactic works only if one ‘wants’ to believe that the smaller group, is actually representative of the larger group...why anyone ‘wants’ to believe such nonsense, is known only to them...