I attended schools that had pretty abysmal math teachers and curriculums. When I eventually slogged my way to the upper level math courses in college for an engineering degree, I was so frustrated with my early education. I feel that so many years were wasted going over the basics, and in reality kids are way more capable of grasping math concepts at a young age than the US education system normally allows for.
Like this article states, we don't need to be teaching calculus in middle school. But there are principles and general concepts that can begin much earlier. I find a lot of kids now hate math by high school, and I feel strongly that is because we as a society are dramatic about the 'difficult high school courses'. With good teachers, it is entirely possible to introduce concepts at a younger age so that the jump from learning a number line to algebra, geometry and calculus doesn't feel so massive.
No company is capable of moderating all of the things a parent wants to keep from a child. That has to be a household controlled issue, and it takes a lot of work to monitor what your kid is doing. It is the same as anything connected to the internet. Some people are crazy/mean/bad influences/dangerous. No moderation will be perfect, so it is more important to understand what your kid is doing and give them guidance. Otherwise, ban them from interacting entirely.