There are three things that make sense to me.
Firstly, if you are big enough, you can manage/architect your data centre better than a cloud provider. You can afford to hire staff to do it, and they can build something specific to your needs. Companies like this should be on-prem.
(It doesn't matter if the company is "digital" or not. It could be a huge retail chain, or a government agency, whatever. The only requirement is to be big enough that you have big needs and can afford a big spend on staff.)
Secondly, if you are small enough, you really, really don’t want to know about routers, firewalls, the OSI layer, SHA256, RAID arrays, etc. Dealing with that would mean another couple of full-time employees, and you can't afford that. Companies like this should be on a SaaS (ideally one less full of gotchas than Heroku).
Thirdly, if you are in between, you have the capacity to deal with system administration, there are some advantages to being able to shape your infrastructure to your needs, but you really don't want to get into real estate and millions of dollars of CAPEX. Companies like this should be on rented physical hardware.
What doesn't make sense, at any scale, is renting VMs.