It's not about current market share but about adoption rates. Which container technology/toolset/ecosystem is more likely to be adopted by the average software shop today?
I am currently using Nomad which works on multiple platforms and that is a requirement for my particular setting. I don't currently use containers in production environments and only see negatives to introducing them into this particular setting. This is not general advice to use nomad, just a counterpoint to any particular fad tech being an industrial requirement.