Providing cloud hosting would require a huge investment, infrastructure, staffing, etc.
No it wouldn't. They can just get space on Amazon or Google cloud. And they wouldn't incur a dime in expenses until they had paying customers using it.
They wouldn't have to invest in any new facilities or any new employees. Or if so, perhaps one new employee to handle the cloud deployments and management. The typical Xenforo customer would probably use about 50 cents worth of cloud computing a month and Xenforo could probably sell it for around $15 a month and get a ton of customers.
Definition of Cloud Computing:
"Cloud computing makes computer resources, especially storage and computing power, available on demand without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet"
Isn't that what we'd all reasonably call "shared hosting?"
No. Cloud hosting is not shared hosting at all. Shared hosting is when you're packed on a server with a bunch of other people and if the resources you need happen to be available when you need them then you can have them. But if they're not, your site will slow down or not be accessible at all. Cloud hosting - while I agree it's just a marketing gimmick to call it cloud - but it has come to mean something that's very different from shared hosting.
With shared hosting you buy and pay for a certain amount of storage, bandwidth and processing power per month. You buy and pay for what you think will be the most you'll ever need. But 99% of the time you'll never need all that you're paying for. And during that 1% surge you'll probably need a lot more than you're paying for and your site will go down.
Unlike shared hosting, cloud hosting gives you true unlimited storage, bandwidth and power. Your site will run as perfectly if you get 20,000 visits per minute as it will if you get 2 visits per day. More resources in bandwidth, storage and processing power are available than you could ever possibly use. Yet you don't have to pay $200,000 a month to have all that available to you. You only pay for what you use.
And cloud hosting in the context of an online platform such as a forum, has come to mean that the forum provider will be completely responsible for all updates to the software. They'll be the ones who configure everything and make sure it keeps running. And it should be them, really, when you think about it - because they're the experts in this software. You'll never have to lift a finger or touch a thing and the software that runs your site will be constantly and instantly updated to the very latest versions as soon as they're released. And you've seen several comments above from people who say they're tired of having to manage the software updates and configurations. That is indeed a time-consuming pain and I too would be willing to pay a little more to have someone take care of all that. Especially if it came with access to this huge "cloud" infrastructure that could handle any load I could possibly ever put on it without charging me for the vast majority of time when I put no load on it at all.