I don’t think this is true. The test harness for certification just commissions a device, and then starts to use the clusters on the device. I don’t think that you can require the user to create an account, and certify a Matter device.
I am at least not aware that a single such Matter device exists, and I have tested many! E.g. the Tado thermostat, which is really designed as a cloud based thermostat. However, their latest Matter enabled Thermostat X you can commission first thing with HA, and use as a regular Matter thermostat no problem. You just loose all the features they offer (including software update, since that is not mandatory within the Matter standard - and they opted to do their own/propertary firmware update).
There are some devices which got launched pre-Matter (e.g. WiZ bulbs). Those you obviously need their App to even download the first Matter firmare. But from then onwards, you can delete their account, use whatever reset machism they have, and commission Matter without using any of their stuff.
In the end, currently it really seems that Matter device do hold their promise: What is covered by the standard is local, and vendor (app) agnostic. But I guess we’ll many devices which only unfold their full potential with the app… But in the end, that is the state of IoT anyways 
So at least with Matter we have a standardized baseline. And my hope is that there will be more companies like Eve which just simply make solid “no-frills” Matter device 
Yeah, but the Matter standard also mandates that all features which are covered by the standard must be exposed through Matter. E.g. you cannot release a smart bulb which can dim only through their app, since that is a feature of Matter.
Update: I thought I’ve read that at one point, but I tried to find that statement in the standard and wasn’t able to. What definitely is the case all mandatory clusters for a particular device type a device is certified for must be implemented (obviously). But it seems that Matter optional features could remain left out, even if the device actually has that feature 
What might happen is that a particular device stays on a old version of the standard which did not yet cover a particular feature… But that is just the nature of things.
I think a lot will depend on the “quality of the Matter implementation” of Matter devices, especially as more and more complex devices get standardized.