Here are just few other considerations for any proprietary platform:
Can your content be easily exported from the platform if you decide to stop using it, or if they decide to pivot?
Can you collect email subscribers, and can they be easily exported from the platform should you decide to move?
Can you syndicate your content, in full, via feeds like RSS?
Can you dictate the terms of when your followers see your content, or are you subject to the whims of algorithmic surfacing?
When a visitor comes to your site, is your name or brand the hero? Or is it the platform’s brand?
Do you have control over the comments section and who gets a voice in your world?