A few times I've seen it enforced at the gate at TPE. They seem to target a few people that obviously have too many bags.

Once at SGN. At check-in the guy advised that the airport authority were enforcing limits. I think the deal was: 1x7Kg bag plus brolly, laptop etc. For C or F you got an extra 7Kg bag. He said that EVA didn't worry up to 12Kg per bag, but that this was not official. I was in deluxe, with a 10Kg bag. The security girl weighed it and said it was too much. I showed her my gold card and suggested EVA thought it would be OK up to 12Kg, and she said "OK". SGN don't seem to worry so much now.

I've seen gate enforcement by EVA at LHR. Sometimes they've explained this by saying they're sorry but its a full flight. This has happened less recently since LHR itself imposed strict limits.

These days typically I have just a shoulder bag, and though pretty heavy and above the limit it never looks much and nobody worries. Everything goes into that one bag - including laptop.

Although outside the ambit of your question, I get really annoyed by people who wildly exceed the limits. But at the same time the 7Kg limit is rather low and even more inappropriate for someone flying C or F. The result of all this is your annoying experience - adhoc and transient clampdowns.