I feel this is one of those "repeat it until it is true" marketing things, like "apple believes privacy is a fundamental right"
But really, I think vscode, browsers and apple products only tangentially secure because business goals, features and convenience trump these kinds of broad statements.
I so wish it was otherwise. There are so few islands of common sense in our world and the water level keeps rising.
Now, whether the browsers or mobile OSes actually are secure because of that, is a separate thing, but those are good steps to take.
It's great that they took security into account during the design phase. I wish they had also taken into account user empowerment. They sandboxed all the apps and in so doing made interoperation, plugins, patches, mods, etc basically impossible. Now the most widely-used form of personal computer is more like a portal to digital services than it is a computing platform. It's sad to see, and I refuse to believe that it's one-or-the-other when it comes to security vs power.
I think that many software people do this. It's likely that you are more familiar with a browsers development cycle.