But someone from Microsoft probably Joe Belfiore said that windows 10 for phones is feature complete
That's not what Belfiore actually said. This was the headline:
Microsoft execs say Windows 10 Mobile 'is significantly feature complete', hints at Surface Phone | Windows Central
Being "
significantly feature complete" is not the same as being "feature complete".
Within the article Belfiore is quoted as follows:
We'll put features in right up near the end. But in general, the broad feature set is set.
Putting "features in right up near the end" means W10M isn't feature complete now!
Anyway, starting with W10M the whole concept of being feature complete is pretty much outdated, so even Belfiore saying W10M is feature complete doesn't mean what most people think it does.
Ask someone to describe what parts of W10M remain after removing ALL the apps (mail, groove, photos, contacts, dialer, etc). Most will have very little to tell you. That part which remains is the actual OS however! Starting with W10M, that part is the
only part that need be feature complete when MS releases W10M to OEMs. The 1st party apps however, which is normally all consumers care about, needn't be feature complete, as practically all of them are now distributed through the store rather than being bundled with the OS.
From here on out, almost all those apps will be updated continually, and you can bet your bottom dollar the first such update will arrive mere days after W10M is RTM'd. Given this reality, what does it mean to consumers for the OS to be "feature complete". I think pretty much nothing...