Maxperson
Morkus from Orkus
No it's not inept. Those non-gods cannot grant spells to the same degree that gods can. They cannot grant the warlocks as much spellcasting power as a god can a cleric. Again, gods in D&D are not all powerful. In fact, they have been highly limited in what they can do since 1e. Just be grateful that the lesser and demigods can grant clerics max level spells these days.It’s Inept when a god can’t do it but a lesser being like a powerful but non-god celestial, fey or fiend can grant arcane powers...

Different beings can do different things.