Ah that’s a shame. It happens to me as well, so far less than half but still, I don’t get it. If you aren’t an established and super famous artist, you should try to get as much as help as possible to reach a wider audience. By not spending a couple of minutes to say thank you to those spending their spare time to do so (especially when they requested it), what they are achieving is that you won’t want to help them the next time they put new music out. I mean, I think it is simple human decency to say thank you when somebody does something for you (always but even more so when it is for free) but even if you ignore that, do it because it will benefit you in the future too. I really don’t get it.