Your probably meant to like it.
We've had a similar discussion with new users on occasions with regards to thanking people for identifications. Yes, we can understand why people might want to express thanks, and even why people might like to receive thanks. But doing so had the effect of adding noise to uninvolved active users' feeds via the then notification systems (changes and unread) so there was a consensus that the expression of thanks should be used sparingly. (Before the 2014 changes, when unread was usable, if everybody had gone around expressing thanks it would have made unread unusable.)
A like/thank system would have allowed notifications to be restricted to the addressees only
The dynamics of the forums are different, but the avoidance of public clutter may be one of the reasons behind the adoption of like systems on social media. (Like counts also act as a sort of popularity/reputation indication, but as often as not it's just a marker as to who is part of the in clique, and acts as an exclusion mechanism as much as an inclusion mechanism.) I haven't thought about the topic before, but there's probably sociology/pyschology/informatics papers out there on the operation of like and flag systems.
On another forum my likes to posts ratio was well down the rankings, so I thought I wasn't a particularly admired participant, until I was nominated for poster of the year in the annual forum awards. In hindsight my reserved and sober mien may have affected the likes to posts ratio.