If you record in a large hall with rich reverberation, the sound can be greatly enhanced. However, if you were to record the same singer in a small room with little or no acoustic treatment, the sound may be unacceptable.
In general, we only use the ambient sound of the room if it is an exceptional acoustic space (like a cathedral or a symphony hall). For almost every other situation, we use various acoustic treatments to minimize the room’s “sound”. By capturing the voice “dry” — with no identifiable “room sound”, the voice will more easily fit together with the other sounds in the final mix.
In radio, we strive to hear the voice with as little of the “room” as possible.
A typical radio studio, or home-office studio, may be only 8 x 10 feet with a 7 foot ceiling. Reflections come back to the mic’s position very quickly, with enough audio energy to be annoying. This is part of the reason we speak so close to the mic… well, ego figures into it, but that’s another subject. Basically, the closer you are to the mic, the less of the room will be heard.
A radio studio usually has some amount of acoustical treatment (foam on the walls, maybe something on the ceiling). A home-office studio likely has nothing but hard, parallel walls, and hard furniture. Even up close to the mic, you may still sound like you’re talking in a tunnel.
Yes, a mic processor with gating can help to some extent. But the gate is only active when the talking stops. During speech, the reflections are clearly heard, and contribute to an indistinct and unclear sound.
Small rooms are a big challenge. Ideally, you would speak in a padded cell (think of a voice-over booth… nothing but foam everywhere). I, for one, try to avoid padded cells.
Do as much acoustical treatment as reasonable. Use a mic with a narrow pickup pattern. Consider a dynamic mic for its reduced sensitivity (some of the most popular mics for radio are dynamics like RE20, SM7B, PR40). Keep the mic close to the subject. Use a downward expander to reduce the background sound when the subject isn’t speaking.
Now you just need to remember to say something important when the mic is on.