It happens when they have a large sales force in the field and the customer believes what they are told. I once used a SCADA system sold by one the said companies which needed some upgrading after about 5 years. The person who actually sold it to me said "XXXX I don't think I have heard of that brand, where did you say you got it" Totally unsupported because they moved onto something with a better profit margin. That was one for the bin and a Citect system went in.
I now only deal with companies that will support their equipment long term, and are not just resellers of obscurely branded imported products.
Regards Alan