In Original Sin, summons were powerful because your resources were AP (which you get every turn) and Cooldowns (which allow you to use the same thing after a certain amount of time). That meant you had to be restricted in the amount of summons because they were low action-economy-cost for you, high action-economy cost for the enemy.
In 5e, summons tend to be of low threat and cost spell slots, which you can't get back during combat. The resource model is different, so the action economy cost is different. So there's no reason to nerf summons in BG 3 as far as I can see.
