What's Holding Back the serum anion gap formula Na Cl HCO3 Industry?

https://anion-gap-widget991.opalvector.com/posts/can-the-anion-gap-be-used-to-monitor-treatment

Use our serum gap calculator to rapidly calculate the anion gap from sodium, chloride, and bicarbonate values with accurate lab interpretation. Ideal for clinicians, it assists electrolyte analysis, acid-base assessment, and quicker patient care decisions