By increasing the material's glow past the limit, the bloom is "activated" by it sooner, making other bright things in the scene less bright by comparison. So those other objects shouldn't glow anymore. Set the object's glow really high, past the limit, then play around with those bloom settings again.
In marmoset, you can almost always manually enter a number, if there's a field for it. You can set emissive intensity to 50000 if you want, there's no cap.
What I had been doing was messing with the emission slider and bloom effect under the camera settings to make the glow stronger because it wasn't bright enough when maxed out. Every tutorial and forum post I ran into on this issue said to do those two things but it still wasn't working the way I wanted it to. Also how did…