I thought there was a bit where he said you only played on one plane. I got three hours of sleep, so maybe I imagined that
And yeah, that will get you wrecked past the first few missions. Really have to get used to having proper units to counter enemy attacks. At a certain point you have to start using the different planes as the enemy will be attacking you from the top and bottom. One fun thing to do is to send a big attack force straight on and then send in a fleet of salvage corvettes in from underneath while the enemy is distracted.
Game gets crazy later on, especially with the scaling. If you have 100 ships you can bet the enemy has that and more. I remember Homeworld 2 bringing my at the time weak pc to its knees.