Don't downrate, (s)he's right. If you are going to paint something, paint a sample foamboard or something and view it in the right context. It is remarkable how the color of paint can be affected by its surroundings as it refracts and reflects. It will look rather unlike the pictures in the catalog if your lighting conditions are different.

I used to work in a paint lab. Things things that also affect perceived color include:

- Undercoat color

- Number of coats

- Gloss Level

- Size of colored area

- Surrounding Colour

- Combination of tinters used by each brand. (Different tinters can make colours metameric)

- Light Source (Incandescent, D65, LED, Fluorescent)

- Monitor Color Space (sRGB, DCI-P3)

- Color Space / Model used for conversion (Lab, Luv, Lch)

- Colour Difference dE Model Used (CIE76, CMC, CIE00)

- Precision and spectral range of the spectrophotometer used.

Etc

More like "fundamentally impossible". Even ignoring the limited colorspaces due to choices of primary (i.e. the fact that no laser's color can be emitted by a screen), and assuming you calibrate your "white" (most screens are overbright these days), it turns out the pigments are really bad at "reflect exactly this pure-ish wavelength and absorb everything else", which is very frequently done by emitters.