I do agree that gatekeeping gets us nowhere. Therianthropy is already such a difficult thing to experience that therian pups need support, and the therian community should always strive to be a welcoming place to all involved. Even those exploring their identities, if they decide in a couple years that therianthropy isn't how they want to express themselves, or that they don't actually align with therian values and identities, that's okay! Hopefully they'll come away more educated and more intelligent about this community. If we "lose" a therian, hopefully we'll gain an ally.
One thing I don't like to see, on the other end of the therian spectrum, is therians who endlessly "belittle" non-therians. I understand disapproving of people who create trouble or perpetuate stereotypes or bully therians, but it gets to a point where I see therians belittling those who may be open to learning! Even if a kid isn't a therian, keeping them as an ally and educating them on therianthropy is one of the best things we can do for the community. Gatekeeping and saying "oh, the normies just don't get it and they never will" makes people defensive; being defensive will make them aggressive, and then you've just created a whole new source of hatred for therians rather than having a logical discussion on the internet about what you experience and how they can relate. Everyone has felt out of place or misunderstood at some point, even those who are not therians. Appeal to that! Educate instead of shaming! we can show them that even if you leave a community, you can keep friends and maintain healthy social interactions.