I think a big part of it is that Docker failed to expand much beyond their initial offering. They tried, but weren't able to get much traction. HashiCorp probab

I think a big part of it is that Docker failed to expand much beyond their initial offering. They tried, but weren't able to get much traction. HashiCorp probably wouldn't be IPOing with a multi-billion dollar valuation if they continued to focus mainly on Vagrant.