I've discovered that when you start getting really cynical about the actual need for a web application - especially in B2B SaaS - you may become surprised at how far you can take the business without touching a browser.
A vast majority of the hours I've spent building web sites & applications has been devoted to administrative-style UI/UX wherein we are ultimately giving the admin a way to mutate fields in a database somewhere such that the application behaves to the customer's expectations. In many situations, it is clearly 100x faster/easier/less bullshit to send the business a template of the configuration (Excel files) and then load+merge their results directly into the same SQL tables.
The web provides one type of UI/UX. It isn't the only way for users to interact with your product or business. Email and flat files are far more flexible than any web solution.