I've been thinking about this. I think I would say: hide posts for the duration of the browser session and localized only to that tab, yes, eminently doable, and they won't return while you browse around until you exit the browser. But for permanent storage, we have to store the ID of each post in perpetuity, and this will necessarily grow to epic proportions over time as you hide stuff, but there is a small upper bound (5MB) on how much can be retained persistently across all apps. In addition, you'd be carrying around the ID of every post you've blocked before and it would be visible to other tabs in your browser, which is a small security concern insofar as it vaguely indicates your preferences. So there is a security and performance negative to this. I don't think we should retain any such information, only generic information such as on/off states, etc. Hope this is clear.