Everyone most certainly does not do this.

Source: I’ve seen a lot of demos that would have benefited from this and am responsible for a group who is not yet doing this, but needs to begin doing so. (I agree it’s elementary tech sales, but it might 201 level as a lot of places succeed without it; we’ve been selling to semi-captive internal customers so long that we didn’t prioritize this. Other companies clearly get by without this as well, even to fully arms-length customers.)

I worked with a bunch of startups and none of them did this.

I hate to say it if you're sales people are not doing this, especially technical sales, you should hire a different team. This is literally sales 101. Especially for a commission based/incentivized job this is first year stuff,