This should still be fixed, easiest by a condition that allows to apply a template to all pages using Gutenberg. These pages need a section with the page width to live in, so it looks like other pages.
On the other hand, for Bricks pages you mostly will add the whole section and its content, so no template is necessary. That’s one annoying thing, that makes my and certainly many new comers life harder. Especially as it seems the biggest builder Elementor allows this and many people finally switch from it to Bricks.
It’s often the small things, that can have a big impact.
Adding a CPT just to distinguish Bricks vs. Gutenberg build pages is a workaround, but not a professional one and something that adds any value, besides fixing a Bricks inconvenience.
I have to say that since moving from Oxygen to Bricks this is the greatest inconvenience I’ve found. In Oxygen I can drop into a page or a template, an area of content which is taken from Gutenberg. In this way a client can write or update their content in Gutenberg without messing up a page or template design. So simple and effective. Why this is not possible in Bricks is just beyond me.
I believe that a custom taxonomy for a page is a common practice. When developing a website, it is not difficult to add this.
What is written above is that it is in Elementor and it is because of this functionality that I have to spend a lot of time copying the content, since the user thought that it was possible to create pages both in Gutenberg and in the Elementor