EEVEE volumetric limitation

Does anyone know the (technical) reason that EEVEE’s volumetrics can’t take advantage of the irradiance volume?
I’m trying to create some steam coming from a bathtub, but I have to rely on billboard particles because of this limitation, as the room is almost entirely lit by indirect light. While this isn’t changing anytime soon, I am curious as to why.

Eevee is interactive scanline tech, features won’t just work with each other near as easily as in Cycles.

Eevee’s tech. produces renders far faster than Cycles, and noise free as well. The tradeoff is that you need a lot more code to allow the various features to take each other into account, and it’s not a job done easily or quickly.

As of now, Eevee will not be getting new features until after 2.8 is released next month, maybe 2.81 and 2.82 will see some of those limits tackled. I think volumetrics is actually not that easy to do if you want interactive or otherwise extremely fast speeds, which is why the current implementation only works well with box volumes.

True. Rasterized volumetrics are almost always implemented as camera-facing planes, if I remember correctly. Mapping textures onto it in a sufficiently efficient manner is no small feat.
My current guess is that it’s hard to sample the irradiance volume without normal information, considering that lighting is stored in spherical harmonics. (I know almost nothing about spherical harmonics, so I have no idea how easy or hard it is to sum the total energy of the probe)