I just did an experiment and checked the top trending posts on steemit, none of the first 20-30 posts has it.

You're right, none of the big players ever burn anything. They don't want to lose their money. And they don't seem to care about the long-term prospects of the STEEM token.

question its efficiency

It is impossible to say that burning does not give anything at all, because burned tokens will not be sold. But yes, this is more of a way to attract curators than to achieve real market goals.

I believe the content shouldn't be estimated mainly by what has been set to be burnt

I still hope that someday we will get closer to the point where the more interesting the content, the higher it will be rewarded. Only this approach can create a healthy economic model. Competition for quality always leads to the movement to the best.