Battery life mostly depends on how you use it and the size of the battery.
If you turn off the dGPU, set some reasonable power limit for the CPU and have a reasonably sized battery there's no reason a gaming laptop should have worse battery life than some low-power piece of shit. In fact the higher binned CPU might make power saving a bit easier, actually.
If you game on it full blast (actually impossible to really do on many laptops since they are power limited on battery alone, but it's OK if you only use EITHER the CPU or GPU at full throttle) then battery life will naturally suck, but who plays games in places where no socket is available, so that's a moot point, no one cares.
For programming, writing, browsing and the like you can get as much battery life as you could reasonably expect considering the size of the battery.