[template] interoperable implementations should always be a success criterion

[npdoty]

For groups that don't intend to move specs to Recommendation, the template suggests removing any mention of independent interoperable implementations from the success criteria section.

Interoperable implementations should be a success criterion for every Working Group. Publishing Candidate Review Snapshots that never see interoperable implementation should be a clear failure condition.

Also:

All new features should be supported by at least two intents to implement before being incorporated in the specification

This is not a success criterion, but an entry criterion. This does not demonstrate interoperability as a success criterion: that multiple browser vendors intend to ship something does not mean that they did ship and that it was implemented in an interoperable way.

[plehegar]

Note that, with the current process, the check of interoporable implementations is only when transitioning to PR:
[[
must show adequate implementation experience except where an exception is approved by a Team Decision,
]]
https://www.w3.org/2023/Process-20230612/#transition-pr

For a Candidate Recommendation, the Process only requires{
[[
must document how adequate implementation experience will be demonstrated,
]]
https://www.w3.org/2023/Process-20230612/#transition-cr