WHY DO LITVOCKS ALWAYS SAY TACHNUN??

“How is the fact that someone in Baghdad did not say tachanun affected what happened in Vilna?”
I didn’t say it did (although, as a side point, I might contend that it is relevant). The poster was implying that the only reason not to say tachanun is if you’re “looking for excuses” not to.

“Chassidim changed minhagim of their communities, not litvakim.”
This is largely a fallacy, but one with so much traction that it would be hard to contend. At the very least, the second clause is easily debatable: how could any of minhag lita that is based on the Gra exist before the Gra? That means they at least changed those minhagim. In any case, I’m not defending skipping tachanun for a Rebbe’s Yahrzeit or anything like that; I just don’t think tachanun in general is as big of a deal and Litvaks like to pretend. Bare in mind, many if not most Litvish yeshivos skip korbanos every single day. We all have our weaknesses.