While traditional hollandaise sauce uses only egg yolks for richness and emulsification, you can technically make a version using whole eggs, but the texture and flavor will be significantly different, resulting in a thinner and less decadent sauce.
Hollandaise sauce relies on the emulsifying properties of egg yolks to bind melted butter and lemon juice (or vinegar) into a smooth, creamy sauce. Egg yolks are rich in lecithin, a natural emulsifier. Whole eggs contain both the yolk and the white. The egg white is mostly protein and water. Adding egg white dilutes the fat content and lecithin concentration, making it harder to achieve a stable emulsion and resulting in a thinner, less rich sauce.
If you choose to use whole eggs, you'll need to adjust the recipe to compensate for the added water. This might involve reducing the amount of liquid (lemon juice or vinegar) or increasing the amount of butter. However, even with adjustments, the final product will not have the same luxurious texture and flavor as traditional hollandaise made with only egg yolks. The sauce will be lighter in color and have a less intense eggy flavor.
Here's a comparison:
Traditional Hollandaise (Egg Yolks Only): Rich, creamy, decadent, stable emulsion, intense flavor.
Hollandaise with Whole Eggs: Thinner, less rich, potentially unstable emulsion, milder flavor.
If you're concerned about wasting the egg whites, use them to make an omelet, meringue, or add them to scrambled eggs. Don't compromise the quality of your hollandaise sauce!