I don't think that's the best conclusion: these days, disk is cheaper than it has ever been, and that "foundational" 8 GB will serve all the Flatpaks you want. Installing apps from packages sprays the same dependency shit all over your system; Flatpak was nice enough to contain it, so you immediately noticed it.
It's at best a mixed bag which makes it harder to fine-tune apps on your system and with limited security benefits (which again become harder to improve yourself).
I don't think that's the best conclusion: these days, disk is cheaper than it has ever been, and that "foundational" 8 GB will serve all the Flatpaks you want. Installing apps from packages sprays the same dependency shit all over your system; Flatpak was nice enough to contain it, so you immediately noticed it.
Flatpak is a good idea.