I think you're looking at it backwards.
Nobody is arguing that Moore, Lankshear, Vuskovic or any other young player should be handed a starting place because they have potential. The issue is that Spurs have a long history of not giving academy players and young signings enough opportunities to develop into first-team players.
If the standard is that a teenager must already be better than established internationals before getting meaningful minutes, then almost no youngster will ever break through. The reality is that players improve through exposure to first-team football.
Look at the clubs that consistently develop young talent. They don't wait until a player is the finished article. They give them minutes in cup games, Europa League matches, dead rubbers and substitute appearances, allowing them to grow into the role.
We often spend years saying a player isn't ready, loan him out, loan him out again, then eventually sell him before finding out whether he could have contributed. Meanwhile, other clubs are integrating 18-21 year olds into the squad and increasing their value on and off the pitch.
Of course young players should compete for places. But competition only works if they are given a genuine pathway. Too often at Spurs, the pathway exists in theory but not in practice.
My argument isn't that every youngster is a future star. It's that we are poor at identifying which youngsters can become future stars because we rarely give them enough meaningful first-team minutes to find out.