It seems to me that maybe Catholic congregations are perfectly willing to sing if they are forced to - by forced meaning that there is no amplified booming cantor’s voice up front to make up for their lack of participation. I kind of wonder if maybe cantors can sometimes be the problem. After all, why sing if you’ll be drowned out by the cantor? Perhaps congregations will sing if they are faced with the prospect that there will be no music if they don’t make it themselves.
I believe you have a legitimate concern regarding this. As a cantor and professional opera singer, I always try to be aware of this when I cantor. Thus, I don’t sing with a full, operatic voice and stand as far away from the microphone as possible. I actually don’t like microphones, espescially since the majority of my singing is done without the need of microphones. It feels encumbering and fake to me, but I also realize that because most hymns are in the mid range of voice, it’s not going to cut across the room the way it is supposed to if we are leading as a cantor.
I do know that congregations do like to have a cantor with a well-trained voice or at least a pleasurable, untrained voice that will stay in tune. Some cantors do stand too close to the mic and will overpower the congregation. If the congregation is not a singing parish, it can deter them from singing more because they can’t hear their own voices when they sing and that can sometimes be disconcerting to a person.
An organ or other instruments can produce the same negative effect if they play their organ or amplified instruments too loudly. I mentioned this in my earlier post, but my parents complained to me about that last weekend with the substitute organist. He played too fast and way too loud. They love to sing everything and felt forced to not sing mainly because of how loud he made the organ and the tempi that he chose. My parish also has a priest who sings with a booming untrained voice into his lappel mic and does actually drown out everyone - including the organ.

A co-worker of my husband’s who goes to the same parish was lamenting to me how he felt like it wasn’t worth it singing whenever father presided because of how loud he is. This is a parish that LOVES to sing. I’d say 90% of the congregants sing.
I have the feeling the kind of cantor you are concerned about was either just never taught how to sing with a microphone in church, which can be remedied very quickly by the music director or the priest, or he/she is someone whose ego has gotten in the way and needs to be gently reminded that they’re there for God and for helping lead the people in song and not as a soloist.
This is also at my parish (I usually cantor weekly at our Cathedral, but will once in a while do it at my parish), but the music director there was telling me that he received unkind feedback from some of the cantors when he suggested in a mass email that we’d try to make a point to stay as far away from the mic as possible since our parish is a great in terms of singing. We would only be closer to the mic when doing the verses of the psalm and the Gospel Acclamation. He wanted us to help the congregation along when it sounded like they were having trouble with a hymn, but to not sound like a solo, amplified voice over the congregation. We don’t even sing into the mic for the Sanctus, Christ Has Died, etc. because they sing so well. We’ll just lead them in with a gesture, if that. That particular congregation doesn’t need us during that part of the mass. They sing so well on their own and I agreed with the organist’s suggestions. There is a reason why we are called “cantors” and not “soloists”. Now it’s a different story at other parishes, as some don’t sing the way this parish does, but for this parish, it actually works very well.