I'm sure what you're talking about is a lot of people's worries. Including me in it.
I also believe that what you are talking about today will someday or at least in the not too distant future will change. The "reblog" restriction mechanism will become a reality.
I agree with you Mr. @galenkp, it should be limited so that someone chooses what to reblog.
The tendency of a person/community to reblog a post at this time just because of the pursuit of points or wanting to appear paying attention. Even I dare to call it attention seeking.
In my opinion, the mechanism to reblog a post is not only limited as you say, but also must be accompanied by an argument column that explains several reasons why someone or a community chooses to "reblog" a post. That would be fairer as a liability and it would actually separate out what was trash and what was quality.
I think this review of yours has represented my own dismay and perhaps also that of many here. I still hope, the reblog mechanism is reviewed by the authorities here to provide convenience for many people and I really have to voice this post of yours by reblogging it with great respect for you. I can take responsibility for it.
You raise some interesting issues; I quite like the qualification idea, a few lines on why the post is reblogged.
I'm a nobody here, I have no sway or influence on decision-making but I am able to have an opinion and on this matter my opinion is above. I think it could work better than the current wholesale reblog process and have more value for all but, of course, only those who make operational decisions could make it actually happen.
Thanks for your comment.