webview app on app store, will it be accepted?

You yourself have summarized the actual status, which is that there is inconsistency.

The Apple app store submission guidelines says:

Apps that are not very useful, unique, are simply web sites bundled as Apps, or do not provide any lasting entertainment value may be rejected

So according to Apple themselves apps which are just web sites bundled as apps may be rejected, but as you yourself have discovered, in practice some people do apparently get this type of app approved, but it is probably prudent to assume it has a high chance of being rejected.

So the actual status is that if you have an app which is nothing more than a web site, you simply don't know if or not it will or will not get accepted.

I know that's not the answer you were hoping for, but the situation is there are no exact black and white hard rules that can be stated as fact and nobody can say for certain if an app will or will not be accepted or rejected.

If you are planning on turning a web site into an app, you won't know if it will be accepted or not, so you should plan accordingly i.e. try to think of some additional unique features if possible that could be added to differentiate and extend it over the pure web version, so that if it got rejected you could make some changes and re-submit.