It’s not that, it’s storing the excess energy and converting it to heat, and that heat is then transferred to homes and thus reducing the use of electricity in the winter. Most of the electricity usage of Finland is in heating during winter. So using excess to store heat is a great idea, and using existing infrastructure to boot.
While your point remains somewhat valid, it’s not actually valid to say “native” in the same sense as “native Americans”.
There were a whole bunch of tribes in the area. Some were more influenced by Europe (swedes, Norwegians) and some less (Finns, Estonian, Sami). Surprise to no one, these tribes living in the southern regions were more successful (easier weather), so they expanded northward and thus rolled over the semi-nomadic Sami in a very nasty, but extremely historically common human way.