I'm glad for this comic because that's my problem too >.<;; At first I didn't reply on purpose because I started posting my old comic here for a research project so I needed raw data, but when I started posting new comics for real, it felt weird... I'm a horribly shy person so it took a lot of courage to even reply to comments that actually asked about something, but eventually even to those that didn't. Then the comments left were those "This is beautiful" and similar comments and I thought really hard if I should thank them or leave them be - because I remembered years ago on DA there was a fashion of writing thanks under every comment and the other person would write "you're welcome" back just to increase number of comments and thus the popularity of the artwork, and it felt really awkward in my opinion. But then I realized how nice it was to receive a reply to a comment I had written to another comic, and that there may be similar people who would like it... So in the end, nowadays I try to reply to almost every comment I get XD (Though I admit I leave out the ones I don't understand or the unspecific ones like "cool.") It takes hours a day but it can be fun and I even met some amazing people this way! ^‿^
Thanks for giving me the opportunity to summarize my thoughts :)