Not everybody remembers that the numberpad is intended for touch-typing use by the left hand, if you are a right-handed business accountant for instance.

This was to allow for a nearly-universal established workflow where the right hand would shuffle the papers or maintain a pointer at a ledger as the data was entered to a mechanical adding machine, without taking the eyes off of what the right hand was doing. The #5 key with the tactile marker is the home position for the middle finger.

The adding machine sitting to the left of the desktop (sometimes on a cart) didn't need to be observed at all, it printed each entry on the roll of paper as you went along, subtractions or negative numbers optionally in red ink. Which could be audited later if necessary if there were any questions about correct data entry. Printing calculators having a financial mode have mimicked this like forever too.

Nobody would have ever expected IBM to be able to sell a calculating machine of any type without maintaining at least this particular backward-compatibility feature.

So it could be seen as more easily integrated by those businesses adopting their first computer of any kind.

I don't remember having a problem with the numpad. (My current laptops do not have one.)

I do remember having issues with accidentally touching the touchpad.

Now days I almost always have a keyboard with me.