This confuses me, why continue with old tech and not continue with upgrading everyone to fibre to the home?
Because they don't want to invalidate their copper infrastructure. And well, it does indeed cut down on civils, cable replacement, investment in dense populated areas.
A lot of those areas would also have underground cabling. Often with blocked ducts etc. Thats even more costly.
Running fiber overhead on poles is comparable cheap and a lot of that stuff probably needed a refresh anyhow.
Just look at the figures along: 1.7M VDSL lines, 300k FTTH. If you had to roll out FTTH for all 2M homes (cable, DP, civils), it would be a whole different ballpark.
/M