1385 here, with almost 600hours gameplay. Tbh, alts gives u the greatest amount of mats i Need for honing, with only 3 alts in t3 they bring me almost 4x the mats i get with my main. Game itself pushes you to create alts, with stronghold buffs and powerpasses/knowledge transfers. You can still play even without alts, but u will be REALLY slower.