This is all in terms of the stylus/ record interface... As the stylus traces the grooves it impacts the groove walls of the record. Any impact causes a vibration. The vibration causes sound which you can hear at a very low level with your ear up close to the stylus as it plays, even with all amplification turned off. The vibrations in the stylus are turned into electrical signals in the cartridge body and eventually get amplified. But the record also vibrates due to the impact, and this is undesirable because now we are adding more vibration beyond what is contained in the grooves back to the stylus. And it gets even worse because the timing is off. The impact of the stylus and record surface produces a limited amount of energy so, if we increase the mass of the record (or do something like couple the record to the turntable platter that many systems do by way of a spindle clamp) we get to a point where the energy we introduce to the record is used up just trying to vibrate the extra mass. It never gets to a point where it starts vibrating wildly because there isn't enough energy available to vibrate that much mass. If we lower the mass, the amount of energy produced by the stylus/ record impact stays the same or nearly so, but now it can excite the record to a greater degree because it is lighter. There is the same amount of energy available to excite even less mass. Also as we lighten it, the resonant frequency of the record increases and gets closer to the audible range where it becomes more problematic. A typically good resonance frequency for a cartridge/ tone arm is like 12 hz or less, well below the limit of human audibility. We don't want to hear the effects of the tone arm (or cartridge body, or cantilever, etc.) vibrating, so we design it all to have its peak resonance below the threshold of human audibility where we cant hear it, even when it does happen. The problem is, each resonance also has harmonic frequencies which are above the audibility threshold and can become audible (although they are lower in amplitude). So a 12 Hz resonance may not be audible, but its harmonics that might occur at 24, 48, 96, Hz are. (i'm not sure where the harmonics actually fall but I doubt they are that evenly spaced).
Here is another way to think about it. Lets keep the record mass a constant and start lightening up the cartridge/tone arm assembly. What happens? As the cartridge becomes lighter and lighter you reach a point where the cartridge starts vibrating so wildly it will jump out of the record groove. How do you solve that? You make the cartridge heavier. Typically we just increase the tracking force, which while not exactly the same thing, produces the same result by shifting more mass to the cartridge side of the tone arm. With your idea, we would just make the cartridge lighter and lighter so there would be less mass to vibrate. Do you think it would stay in the groove then?
This isn't the same thing as reverb in a venue. Reverb is sound hitting a surface and bouncing off. It takes sound time to move, so you hear the direct sound and then a microsecond later, you hear the reflected sound. You can also get standing waves where the sound just keeps bouncing across the same surfaces repeatedly (very undesirable). A resonance is that sound hitting a surface and making the surface itself vibrate (the sound hitting a surface is also an "impact" just like in the record groove). So the bigger the hall, the more surfaces there are to reflect off, the more reverb. How do you control that? You hang sound absorbing panels which are made of a material which is not so rigid and cant vibrate as much as a hard surface. They absorb the sound waves into a material that isn't easy to make resonate.