Isn't pixel density in default mode actually going backwards?

[BlackZeppelin]

I'm confused about something. Apparently the default display is FHD but can be bumped up to QHD. My current Galaxy S5 is FHD and is a 5.1 inch display. So if you have a significantly bigger display at the same FHD resolution, doesn't that mean that the 2 Galaxy S8 phones will have LESS resolution?

As obviously FHD spread over 5.1 inches makes a more pixel dense concentration than the same FHD at 5.8/6.2 inches.

 

[Cobravision]

The S8 in fhd has lower ppi as the S5, but not by much. Any time the screen grows without an increase in pixel count the ppi goes down. But the S8 has 400 more rows of pixels, so the ppi would be the same as a 5.6" 16:9 screen. BTW, when we say full HD, that's technically 1920 x 1080. The S8 in that mode is actually 2220 x 1080.