Berating people for caring what is put in front of their kids by the Roku homescreen is ridiculous. Yes, the world is scary. Yes, there comes a time kids need to start to grow up and learn about these scary things, but when that is varies and is up to the parents.
Just because people don't want ads for adult horror movies displayed to their kids when they are trying to watch blue's clues doesn't warrant these BS "oh i guess you're going to shield them from wars and halloween and the rest of the big scary world, I guess you homeschool them and your kids need to grow tf up" kind of responses.
Get a grip. It's not much different than a kid playing a educational math or blocks or colors game on android/iphone and having ads pop up halfway though with halfway naked women or scary games or any of that - there is NOTHING WRONG with having a problem with that as a parent.
Yes, there are things in this world we cannot control, but there are some we can, and as parents, do. And this could easily be solved one way or another. There could be kids profiles that limit content to children rated things, and those profiles be excluded from ads, for example. Provide a $1 a month subscription option that removes home screen ads. Put a content filter in place where ads have to be approved by Roku staff. Stop showing ads and make your profit of device purchases. Filter ads based on where they go if you click them. This is not an impossibility.
You are not being helpful by just telling people they're parenting wrong.