Well they do provide the Secure Folder. Where all the apps contents and data is fully isolated from the outside. This is much safer than a regular app lock.
If you'd need to use an app securely, you could install it within the Secure Folder and use it there.
It is not that useful actually. In case of media data, it's fine but in case of app lock it's not good. Because when you secure any app you can't login to the app you secured in the Secure folder. So the dedicated App Locker will be much appreciated if provided.
