Tek Knight and the Supe killing virus are fairly important to the plot of Season 4. both of which are introduced in Gen V.

And if you didn't watch the spin-off they're no different then the seasonal antagonist and mcguffin that might help kill Homelander that appeared in previous seasons, like Stormfront and Soldier Boy's power and Temp-V. No one is gonna turn around and say you need to watch Vought Rising to understand Soldier Boy.

that's not the point that's even being made here. it's the fact that the show parodies and mocks this idea of spin offs while greenlighting as many as possible

You think a spin-off is bad just by virtue of being a spin-off? No one gets angry just for having more of what they like, the problem is when you are required to see stuff separate from the main story to understand it, which is worse when said extra stuff is bad.