I think people often underestimate the value of being able to manage their own destiny. They key point here is "manage" though: you have to actually do it - it's an active process.
If, on the other hand, you simply stick your head in the sand and ignore the situation it will eventually get to the point where it becomes extremely difficult and expensive to deal with due to a variety of factors such as no clear migration path, loss of institutional knowledge, and so on. I name no names, but worked for one UK company in particular with form here.
I'm not making an argument against SaaS (we use a few of them), but it's important to understand the trade-offs you're making in terms of ceding control.
Further, some of the biggest value they will provide is being able to see transactions between vendors. So eg calculating an IP address reputation score by seeing bursts of fraudulent purchases. That is impossible to do in house only.
But that's not what either I or the GP were talking about: we were talking about hosting a product that you'd purchased from another vendor on your own infrastructure.
The obvious downside to that is you don't have real time updates (as well as the usual other benefits that SaaS brings), which is why SaaS suites this kind of business well. But it can be done and was sometimes done this way "back in the old days".
Distributing the database to customers is still workable despite this drawback - antivirus systems are a common example.
I don't agree with that. Having the database only allows bad actors to see if they've been added to the database - not the business logic of how they ended up in that database.
You could argue that knowing you've been added to the database is still an advantage, which is true. But those same bad actors could still test the system with SaaS solutions too. eg when one acquires stolen bank cards it is common to use those details to make small payments for things like food delivery to test if those card have been blocked or not.
I wouldn't say it's preferable for the customer. It's just one of many options.
> but it's obvious why a vendor wouldn't be keen
Yes, SaaS obviously has benefits for vendors too but what's most preferable to them is making money. If every customer refused to do business with SaaS then vendors wouldn't prefer providing SaaS solutions (yes, I know I said "solutions solutions" :P). The reason SaaS is so prolific is because it offers advantages to customers as well.
When has SaaS stood for anything besides Software as a Service? Because software as a solution could describe almost any business model?
Granted there are more cases of when SaaS et al works than when it does not. And I do agree with you that it's no ok to shaft paid customers in this way. But that doesn't mean that it doesn't still happen. This is why I've have to consider the self-hosted verses XaaS debate myself writing Business Continuity / Disaster Recovery / et al plans.
I really dislike this idea that it's our responsibility to ignore inflammatory tones and trolling, instead of it being the responsibility of the poster to communicate clearer.
Back when it was more traditional to buy a software licences and self-host rather than pay a rolling subscription to an XaaS, a service going dark just meant that you were shut out of updates but not the software itself. Sure you'd still eventually need to migrate away but at least you could then do it on your own terms.