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The ESR meter was (and still is) a valuable tool as far as SMPS are concerned.

This became more apparent with the advent of certain satellite receivers such as the Analogue Amstrad SRD510 and Pace PRD800/900 series.
Initially we wondered why they wouldn't work when the caps measured ok via more 'normal' means but worked when they were replaced, and I think it was by a man called Ray Porter in one of the TV mags that first explained what ESR actually was.
Then the various technical departments caught up! and the rest was history, the Peak Atlas ESR meter being a most useful tool in the workshop around this time.