Are they really though? A serverless event driven architecture system I’m working on literally costs less than £10 a month on Azure. Running full blown VMs instead of cheaper more appropriate technologies like containers or functions will always cost more.

As per our calculation for CloudAlarm [0], as we reach a few hundred users, it'd be cheaper to use a dedicated instance than serverless (Azure Functions) design. So it may vary from system to system depending the amount of work you perform for each user.

0: https://cloudalarm.in/ – btw, you may wish to have daily budgeted pace based alerts using it – to inform you when the usage spikes up (much faster than Azure's consumption threshold based alerts).