The argument would be that the opposition mitigated the amount of groups that were doing this. No way to know for certain, but extremely logical to think so.
Would you have made such a claim if not for the מקור ברוך?
His description is definitely not a true account of facts as would be evident to anyone with a shred of intellectual honesty.
It's amazing how much is built and hung upon this supposed "plausibility".
Let's put some facts into context, and then tell me if it is "plausible":
There were 4 Chassidim who were murdered in Swenzian as a result of the רדיפות and חרמות. Do you really think it is "plausible" that the Tzemach Tzedek would have said ANYTHING positive about the רדיפות and חרמות?
I am not disputing the fact that ערוך השולחן visited the Tzemach Tzedek. I don't know how plausible (not very, to say the least) is the account of daily meetings and discussions over an extended visit. I do KNOW that the words (or content) attributed to the Tzemach Tzedek are totally implausible.
And to answer
@EliJelly's question, the only reason why these issues keep on coming up is because there seems to be an insistence to regurgitate claims that have been previously "adjudicated".