I don't know if MLS Next has publicly stated anything about this topic, but it seems to make sense to me to have a pathway for higher level kids that want to play professionally. Playing HS soccer isn't really a piece of that path. Obviously there are concerns of cannon fodder that
@Grace T. rightfully points out, but I think that's the gist of MLS Next. ECNL is high level as well, but they're more focused on the collegiate player. I do think if the US/MLS wants to get better they need to have an academy system that supports the professional pathway, similar to European clubs. Wasn't DA as restrictive as MLS Next when it comes to HS soccer?
High school soccer has certainly changed since my time. College scouts used to come to HS tournaments/games all the time back then.