Ask HN: Is the rapid growth in Hosted PBXs/VoIP hyperbole?

I'm interested in debating and hearing your thoughts the growth of 'Hosted PBXs' in the UK and whether it's a growth in the interest of the end-users or the businesses that supply the service and whether it's going to be a continued growth or just a momentary blip.

I read an article today, discussing a report from Cavell Group, that observed an 11% growth in Hosted PBX seats to 2,423,123 (across 71 suppliers) in the 6 months leading up to June 2016. And then by, December that figure grew to 2,705,027.

My personal stance is that we're seeing a momentary blip. I think one of the most frequently advertised benefits is that it saves money but primarily does so because there's less initial expenditure (eg. it will be more expensive in the long term). In addition, whilst the call costs are typically lower, this can be achieved with an on-premise solution.

I also think the perception that it saves costs takes advantage of the fact that a significant portion of the businesses who switch to Hosted PBXs were previously stuck in the Avaya/Mitel/Cisco ecosystem who are traditionally expensive upfront.

Furthermore, whilst I appreciate a cloud infrastructure, in principle, offers reduced engineering costs.. reduced licensing costs.. etc.. I would argue they don't apply to a PBX, which is most often a plug-and-play system.

Lastly, my personal experience (15 years experience in VoIP) is that Hosted PBXs have been around for a long time. As early as 2003. I've personally communicated with 1000s of customers. The longest instance of a business using a Hosted PBX was 4 years. And only because they were stuck in the contract. I'd be interested in knowing of longer cases.

What do you think? Are the undeniable benefits of 'cloud infrastructure' even applicable to a PBX? Is the growth simply because providers are jumping on the bandwagon (eg. bigger salesforce)? Why would you rent a Hosted PBX over an on-premise option?