"Merchantable quality" and "absolutely perfect" are quite different - I doubt that any IT system has ever been developed which is totally bug-free - even the US space programme then and now has had the occasional bug.Why is it acceptable to suggest that if a business orders an IT system it will come with bugs that need fixing? Any other product you buy should be of merchantable quality, for some reason IT providers seem to hide behind 'upgrades' when what they should be saying is faults, or admit they have developed a less than acceptable product.
The modern internet may look like it has less bugs than earlier decades but in reality it just updates from time to time without the user realising.