Yep, agree 100%, Angie.
That said, it seems to me that when those lists mention "perfect white tee" and shows a picture of a model wearing such a garment (with perfect jeans and perfect black pumps and perfect blazer) the tee appears to actually be a men's version. It reminds me exactly of the type of tee's my dad would wear under his collared shirt and suit, yes as underwear. On a woman's shape it would be relaxed and loose, ala "boyfriend" fit.
It is also about the cotton. When I was a kid, I'd sometimes borrow my dad's tees to sleep in. The cotton was so soft and comfy. So I dunno... I guess I've been looking for that version in my adult life, the same feel against the skin. My dad's tees came in value packs. I have shopped the men's department in the past, but the selection isn't there like it was back in the 70s-80's. Because as office attire has become more and more casual, men no longer wear such layering tees.
The closest I have found to such a tee, for women, is the Vintage tees at Jcrew. They are 100% cotton, not linen or rayon. I have them in scoop & v-neck, and black, white, navy, and neon pink. You have to play around with the size a bit, to get a fluid fit. But yeah... they are mostly for layering and supporting roles.