There might be a time in which we reject such content just as we did with prior widely-accepted behavior that was immoral (like homophobia and racism). Future generations might look down on us because of child celebrities (among other things), and I sincerely hope they do.
You’ve presented no argument as to why it's not alright. Now, this may be a base moral axiom for you, such that no argument is needed, but that's not particularly convincing to anyone who doesn't already take it as a moral axiom.
> There might be a time in which we reject such content just as we did with prior widely-accepted behavior that was immoral (like homophobia and racism).
There might be a time when we see anything in any way you can imagine. That's not an argument that we should.
There might be a time
Movies and TV shows starting children are not unheard of as commercial endeavors. I'm not sure why with YouTube as a viable monetizable video platform, parent-driven productions on that platform are fundamentally any worse of an idea.