Maybe pre-computers the fact that you’d gone the last 12 months without crashing and a single renewal phone call cost a lot less in staff wages than fielding new enquiries and quoting people there was benefit to offering renewal discounts.
Now that its almost all automated, that benefit has largely gone. Every company knows your driving history in an instant, whether 100 people or 1000 fill in their online quote form makes no difference.
Things beyond your control will have changed. Everything is based on an average risk. People in your neighbourhood may be crashing into parked cars a lot, loads of people with your job title might be having expensive whiplash claims.
Also consider that your car has changed even if its the same. A 5 year old corsa may be the car of the sensible and financially prudent office administrator, but a 6 year old corsa may be the chavmobile of choice. When I changed cars – same brand, still a hatchback (10 years newer, 10 times the value, >50% more power) my insurance halved.