Sure, you can claim it's not really work in the narrow definition of work, but if you go down that path, you will end up at "it's only really work if it's physical work".
However, it's disingenuous to compare them with plowing a field, laying bricks, welding steel bars, driving a bus, serving meals or even fixing software bugs.
What may seem like "eating and drinking" for sales and biz dev folks is a game requiring thinking on your feet, subtle negotiation, reading social cues, and constant strategy changes.
Trying to influence a potential client to close a multi-million dollar software contract is anything but close to 'normal' activities. It's very demanding intellectually and emotionally.
I really encourage you to learn more about what sales folks actually do when having dinner with a big prospective client. They aren't just eating.
That shit is difficult, tyring and definitely requires certain skills to do it right. I definitely would put it up there with developing complex Software architectures.