When it comes to Japanese TMA's (not Judo, real TMA's) it is all about historical preservation. That's one of the reasons there are so many flowery names and techniques to differentiate one family style from the next. Lineage is/was important to them for historical reasons.
Pre-MMA martial arts in America used lineage to denote applicability (since there were no cross art competitions) which is not what lineage was originally intended for. If Joe Bob Smith learned the deadly ninja secrets directly from a Japanese master, then he said his ninjutsu was the most deadly in America and he got more money, er I mean students.
At the same time in BJJ there is a bit of hypocrisy. BJJ folks go on and on about how if you want to know who has the best BJJ, go to a tournament. But at the same time, look at the signature lines on this forum alone. Everyone wants to show some short direct line connection from them to either Maeda or Carlos or Helio.
You can't dog the TMA'er for purity and lineage and then put your BJJ "family tree" in bold in your sig line