It’s pretty much spam. Most people don’t like being forcibly added to a random group. If it’s worth a shit people will come on the own.
I agree about it not being a good way to gain a positive community, but I feel some, just some sympathy as there are so many projects about and advertising is so locked down and overpriced. Unfortunately force inviting and bot adding are some really unattractive, short term and counter productive ways that people seem to want to do it