I do not thin that is the case at all. Most Shenmue Fans should now that Shenmue is not Yakuza and Yakuza is no Shenmue.
Yakuza was also kept barely alive for many many years. It was not significant at all. This only changed with 0. Y0 gave the franchise a boast. But before that nobody cared about Yakuza that much.
Und the comparisons between these series are not fact based. In most of the cases that are just troll posts that do not know much about gaming at all.
But that has nothing to do with feeling insecure. Most of the Shenmue fans are old enough to tasted life to it's fullest in every way. Positive and negative.
Most of them are to old to care that much about a video game. Feeling insecure if anybody does not a like game you personally like is not a thing grown up people what do.