Let me tell you a story about a business I worked at.
This business had a CEO who was just plainly incompetent. The sort of person who was first to take credit and last to take blame.
We were operating with IT equipment that was a decade old (yet gifted after the equipment was written off in tax terms). As equipment failed, slightly newer IT equipment was put in place of it, also written off, and the reports went up to the parent business that the old gear had failed because production staff ("So how do I send an email again?") had not reported that it was failing because of bad fans and screaming hard drives. Last I heard, they were still operating with Windows 98 and NT 4 workstations in a couple of key roles, and XP on almost all of their other production systems.
The manager in charge of actually getting things done didn't get a pay increase in the decade I was there, and worked up to 70 hours a week (30 for free). All staff had to make up for the lack of investment by working extra hours for free, and refusing to do so was demonstrating a "lack of team spirit." Hours weren't recorded, legally required holiday pay wasn't paid. Reporting any of this to the authorities resulted in extrajudicial punishment (a visit from some friends of the owner).
The only time staff pay went up was when minimum wage went up. Training was non-existent; you were put in a job, they showed you which buttons to push, and if you didn't get it right you were reprimanded. I saw staff work double shifts for months and then get fired because of an inconsequential spelling mistake, and then the next person in the job (but with half the hours) get away with the worse mistakes for years.
Naturally, there was a high staff turnover. The more skilled the staff, the faster they were gone, but that meant the people who couldn't leave (for one reason or another) had to work much harder.
Ultimately, the business still exists because of the unrecognized and unpaid hard work of the staff, and absolutely in spite of the efforts of the incompetent and criminal CEO.
But what is the point of my story? ROI is seldom "analysed in greater depth" because few rich people want to be liable for the actions of their staff. Last I heard, the CEO was promoted, with the appropriate salary increase, to a second tier position in the parent organization because of his managerial skills.