...promising everything and delivering half of that at best...

I work for a company driven by sales people. It sucks. They keep promising things we don't have and complaining that engineering can't deliver. IMHO a good sales person should be able to sell what we have. Any jackass can make empty promises.

Sales people typically do exactly what they're paid to do - no more, no less. You can shout at them 'til you're blue in the face about overpromising, but, if you've got their pay structure set up such that they can earn more commission by making wild promises, then they're going to keep on making wild promises.

Make them do proper accounting, an empty promise costs more engineering dollars than a believable one, and the difference should not be determined by sales.

The sales process needs both rewards (commission) as well as punishments (commission loss based on unmet delivery). The idea, "As soon as the contract is signed I should get my money." is a broken one as it reinforces the type of behavior that leads to unrealistic promises being made. The 50% at signing and 50% at delivery model is better for this reason. Yes, there would need to be additional language surrounding what an "unmet delivery" would be and how it would be gauged with relation to promises made during the sales process.

In this context, the only thing that matters is whether Oracle's strategy is more successful at generating profits than RedHat's. Is it?

You got half? That's pretty good! ;)

If they can still sell despite having that (very much deserved) reputation, then their sales teams must be pretty impressive.

As Rick James used to say, "Cocaine is a hell of a drug!"