Getting away from it all
In the early days of our company, 1990s, the commercial and technical (Engineering) systems ran on a common system. We make bespoke, high-value products for the utilities. I had written the commercial system based on a simple database and it was devastatingly quick because there were few bells and whistles behind the user-chosen interface (which could be fancy or command-line according to user preference). In particular, product-pricing was simple and the Sales team could look up previous prices, make adjustments for inflation/materials/odd-balls etc. and work up a convincing cost for tendering; it was often years before orders were placed but the quotes could be kept, modified but most important, kept relevant.
We were taken over, largely for our sub-contract ordering. About 80% of our turnover was bought-in, (e.g. motors, controls, metalwork etc.), complimentary products and machinery for auxiliaries around our product. Our new masters enforced their <Big Supplier> 'System' on us which, inexplicably, could not absorb our existing data. Because our 'old' system was small, we managed to keep it under the radar and enable Sales to maintain their pricing policy and history. After five years, I was made redundant but the system was still being used to cost new business.
After several more years and with the company in new and even newer owners, I was tempted back to work there again only to find that the 'old' system was still being used by Sales as they had 'no other way' to keep track of real costs. We were in the process of updating when we had a new boss imposed who introduced a system of his choice. It wasn't bad but he was very proprietorial about it and we weren't allowed to comment, criticise or extract data except through him. I couldn't work with him so I left.
After 18 months he too was gone leaving his system to be abandoned. I don't know if the 'old' system is still there...