Not helping matters is the fact that most of the reformers are themselves ignorant chuckleheads who identify the heuristics that skilled arithmeticians use and codify them as a NEW set of rules to be memorized...
Failure to learn the standard algorithms impedes progress. You are unlikely to do well in the next course if you are slow and can't handle numerous cases.
Learning alternate algorithms is great... once you have the standard algorithms down solid and are ready to prove equivalence.
Have a look at the sample chapter from David Tall's book...
https://homepages.warwick.ac.uk/staff/David.Tall/themes/thre...
That said, I've definitely seen some of that "let's just replace method X with method Y" – how harmful that is depends on whether it is just presented as a default or as The New Standard Algorithm, I guess.
Of course it isn't, because such lunacy wouldn't be supported by competent research. But the people who do education research, the administrators making curriculum decisions, and the concerned parents trolling about the dangers of "Common Core" on Facebook are distinct sets with little overlap.