That is Human Nature. Give a Human a tool, and their ability to think independently outside its pre-established context defined by the group will show in time. That is what separates Man from Ape.
I do not say that to throw out your concerns. They are valid; they become tiny grains of dust and sand flung at mach-speeds onto a windshield’s front, breaking integrity over time, little by little until only another single tiny pebble shatters the entire piece.
I suggest looking at how likes mitigate this “nature’s subconscious deviance” when compared against other tools and techniques employed in other modern forum software available; tools to express approval and build rapport.
As to the car forum mentioned, those moderators should have those behaviors pointed out to them.
Sometimes, all it takes is a little bit of open, honest communication with users, to steer them from unwanted behaviors, now that said behaviors are so prominent that others have become cognitively aware and can now define them, as you did above well.
I said this in another topic on Meta; same concept.
Example: if user A opens a topic, is ignored; user B replies with same topic, gets attention. I would be the one to link to the OP as a reply and gently steer it, meld it into the current discussion so that user A now has an opening to reply and join the topic fully with their words. That I call a “gentle steer” drawn with utmost positive gain, sans negativity as much as possible to keep things smooth. I do it here on Meta when answering support topics, in many various ways. (And upon further reflection, my steer will give others that “oh damn; we got caught not being nice and he just hinted to it” feeling. That refers to my first post in this topic: being the odd one out of the group dynamic that is expected to be harmonious, and not silently berating.)