My expectations of SkipInitialBuildOnFirstBranchIndexing is that any "Scan Organization Folder Now" or "Scan Multibranch Pipeline Now" will be affected by this setting.  What I didn't expect was the webhook events "Organization Folder Events" and "Multibranch Pipeline Events" are also affected by this configuration.

I'd like to stop scans (what I consider branch indexing) from triggering builds on initial scan, but webhook events should trigger builds as something has actually happened on the repository end, regardless of what state jenkins is in.