It doesn't add anything. Imagine your comment was at the top. The linked article doesn't say how to get the effect. Your comment doesn't say how to get the eff

It doesn't add anything. Imagine your comment was at the top. The linked article doesn't say how to get the effect. Your comment doesn't say how to get the effect. So it would all be a bit mystifying. Imagine your comment was in the middle of the page. There would be other comments below yours that would be more worthy of people's time to read than yours. So your comment should appear below those comments. Thus it should attract a few downvotes. Upvoting the link would be more appropriate than posting a generic compliment. If you had said "This is an excellent idea and I will steal it because (a) it will make it easier for people to link to and quote me (b) it will make it easier for me to link to my earlier articles (c) ..." then that would be different: you would be providing reasons, and that might provoke further useful discussion. It might not attract upvotes, but unless you were just repeating what someone else had said it shouldn't attract downvotes. That one second to vote something down is not a serious barrier to downvoting. (Neither is the one second to vote something up a serious barrier to upvoting.)