I agree. I've seen containerization mentioned by many vendors in the last year. It adds another layer of questions to vet like "do they possibly know what they're doing?"
I have a vendor who pitched their new "cloud-native" re-platforming project and it really spooked me. It's data management-type tool that was migrating from a traditional on-prem client/server architecture to an AWS-hosted Angular interface with a MongoDB backend. I got the same pitch a year later and the entire stack had changed. I was spooked the first time; now I'm really spooked and thinking about migrating off the platform.
Whether or not this is a good idea depends on your situation and their level of competence.