Very few organizations are able to stay efficient on the long run as they scale. This is a simple matter of processes being stacked on top of processes and inter-departement frictions. That complexity is inherent to having regulations and laws that you need to comply with that become hard requirements.
For a more concrete example think of HIPAA compliance, during an audit you can have everything on-prem and hope that your IT department actually understand the security and privacy boundaries or have everything in AWS and be compliant because they conform to the standard by default.
> syphon off any profitability
For most of those businesses software is not the profitable bit, it's a cost center like most other things that serve to support operations. In that context, migrating your code to AWS/GCP/Azure means very little cost inflation.