If we got rid of the like reply would we be flooded with lots of agreement posts that have nothing new to say but just wanted to express support somehow?
I am old enough to remember when this was considered a real problem in conversations on the internet. It was called "Me too!" posting, and was considered a semi serious issue in the days of usenet and listservs. Basically, people would quote a post just to say "Me too" with nothing to add, it it would quickly fill your mail box with tons of useless emails. It was considered an e-tiquette faux pas, and often sent the message that the poster was a noob. You will have trouble googling it by name now because the "MeToo" movement took over the phrase, but it is immortalized in the Weird Al song "All About the Pentiums" in the verse where he accuses a technologically inept user of "posting 'me too' like some braindead AOLer".