[smusamashah]

Additionally, this being simplest I wasn't expecting a new page for every category of unit and the added load time with that.

[rpcom]

Having a dedicated page for a category or particular conversion between units, allows adding extra information, such as info about unit of measurement and formula. Example: https://www.betaconvert.com/length/meters/feet

[janalsncm]

You can pull that out of the pathname while keeping the same page.

[fragmede]

Sure, but that's less simple.