Yes, it usually is. But in this case the problem was that the CEO could unilaterally override the decision made by everyone else, so it wasn't just a meet-and-greet.
Yea, it's not a meet-and-greet, as in there can be no impact to the outcome of the interview. You're definitely still interviewing. But, in every case where I got to the point of "You're going to chat with the [Founder|CEO|BigTech VP]," at that point the job was mine to lose. They're not going to waste a VIP's time if they're not serious about making you an offer. You effectively have the offer. Your job when talking to the VIP person at the end is to "sound like a likable, competent person, who VIP would be cool with saying 'yea I hired this person'." That's pretty much all you need to do.
Generally the chat with the VIP means: "You have the job, but I (VIP) want to just double check that my underling hiring managers are not totally useless."
No, you don't have the offer at all. If you did, you would already have the offer letter in hand and the meeting with the VIP would just be a casual meet-and-greet. When it is part of the interview process, it is very deliberately because the VIP has veto power, and thus the decision to hire has not been finalized.
Your job when talking to the VIP person at the end is to "sound like a likable, competent person, who VIP would be cool with saying 'yea I hired this person'."
As you point out, the VIP is the one making the hiring decision. Everyone before the VIP was just a filter before the actual decision-maker.
(Outside of tech) the only time it's normal for a VIP to be involved in the interview process is when they're interview for executive or other management level positions, or for a role that would be working directly with management on a regular basis. But tech likes to do things backward, and insist that a VIP wasting their time on a lower-level hire is somehow normal. It's not normal in any other industry.
The point of my comment (and yours) was that the hiring decision wasn't actually made, because as you point out (again): the CEO's decision was the only one that mattered.
That's a huge red flag for any workplace. The only time you should ever consider taking a job at a company like that is if you're unemployed and you need the job and have no other prospects.
Generally the chat with the VIP means: "You have the job, but I (VIP) want to just double check that my underling hiring managers are not totally useless."