No, it’s not, and the examples on the page you link to are examples of something else entirely. The subject here is “some platforms” and is not deleted.
It has nothing to do with where in the sentence the deletion is. It has to do with what is deleted.
“I like spicy food but my girlfriend doesn’t [like spicy food].”
This is correct deletion, at the end.
“I like spicy food but my girlfriend isn’t.”
This is what the illiterates who made the website are doing. It’s not conversational deletion, it’s just wrong.
EDIT: Also, and more to the point, “conversational deletion”, as defined in the link you provided, is the deletion of the subject of the sentence. This is not what is happening here, as I pointed out. Again, nothing to do with whether the deletion is at the beginning or the end.