Because it is still massive. The 6" Nexus 6 is 3.3in wide whereas the 6.7" Pixel 8 Pro is only 3" wide. Even omitting the bezels, the Nexus 6 has a screen width of 2.94" vs. the 8 Pro's 2.75"
>>kllrno+(OP)
You've highlighted exactly what the comment you were replying to was talking about, the aspect ratio is much different. The Pixel 8 Pro has a 6.7" screen vs the 6" on nexus 6, despite being 10% narrower.