One specific circumstance which impacts me is the Capital One virtual credit card extension (https://www.capitalone.com/applications/eno/virtualnumbers ) which if one clicks on "Get It Now", from a copy of Firefox, one ends up on the webstore: https://chrome.google.com/webstore/detail/eno%C2%AE-from-cap...
Even consulting the page source (view-source:https://www.capitalone.com/applications/eno/virtualnumbers/) shows some mentions of Firefox but certainly no mozilla.org URL or .xpi that would imply they're serious about that claim.