Zardnaar
Legend
I haven't seen the stream but he really ought to begin by stating what he thinks a Warlord should be able to do. If this list doesn't include the buzzwords "non-magical" "healing" "buffing" and "making others take action", then he might just as well not bother.
Making the Warlord a Fighter subclass is a restriction that should have been discussed and questioned before decided upon. Can you really fit all of what a true Warlord needs to be able to do into the Fighter chassi without making it too good?
At least tell me the actions it can make allies take are "real" actions - if there are silly restrictions disabling caster allies from casting non-cantrip spells or disabling martial allies from using "riders" (GWM, smiting, sneak damage, etc) let me just go siiiiigh
Since the character that is the Warlord could have been casting a Fireball or a Heal or making two Smite attacks or making five attacks with Precision and GWM... it really is wrong to think it's too powerful for it to enable its allies strong actions.
The only restriction needs to be on its ability to be all those classes (Sorcerer, Cleric, Paladin, Fighter), i.e. the Flexibility. And really, the only restriction needs to be that it is weakish on its own.
The warlord is supposed to be an excellent fifth wheel, having fun by glory through its allies. I really don't think its ability to command others need any meaningful restrictions. Especially if it eats their reactions, then it absolutely needs no other restrictions (and in fact, the class might turn out needing to be strong in itself, since no min-maxer will be happy to have somebody else use up their reaction)
I really think the Warlord would be best off if built as a standalone class modeled on the Cleric chassi. Not a Cleric subclass; a standalone class with the Cleric's armor proficiencies; a good selection of Cleric-level or at the very least Bard-level healing and buffing (though - and this is crucial - non-magical). That makes it a strong enough stand-alone character. Then add the ability to sacrifice an attack to make an ally do an attack (the class getting two attacks no later than level 6); and the ability to sacrifice its action to make an ally use up its reaction to do an action.
Done.
And that there is broken. Clerics have weak attacks so any warlord that can sacrifice their attack and heal as well as a cleric or druid is OP.
You would need to limit the attack granting or have a weaker healer. At will attack granting in 5E is OP as well due to Rogues, Paladins, Rangers.