Of course, you can always pick and choose where to allow comments and not. It's not an all-or-nothing proposition.

For example, after I published a book on how to develop websites using Bootstrap v.2 and then Bootstrap 3 came out, I just posted the whole book on my website for the taking. Knowing I wouldn't have the time and/or desire to deal with comments and questions, I turned comments off for all those pages from the very start.

But I enjoy engaging with other on my posts, so those are always on. I find I sort of have the best of both worlds: traffic from my book(without a lot of upkeep), and the ability to engage with readers elsewhere. People that are really curious about something I've written where the comments are disabled usually send me an email anyway, which I'm happy to answer.