[oooshha]

They will rapidly find that 90% of their traffic continues to exist within the subreddit, therefore anyone wanting a good thread will post it there rather than on the website, and the website will rapidly atrophy and be abandoned.

[r00fus]

While this may be true ( some currently successful sites are spin-offs from other sites ), often there is an orbiting behavior.

If the option is to successfully monetize a portion of the flow vs nothing, it may turn out to be a net positive for the subreddit admins.

[blueboo]

...but originating from Reddit? There's, ah, voat...

[Vinnl]

Imgur comes to mind.

[slfnflctd]

What's funniest to me about this is how reddit spent a bunch of money creating their own image hosting service, but somehow imgur is still often the better choice.