I have been working on Finnish genealogy for many years, and have been taught by my relatives, including a genealogist cousin in Finland and others on other genealogical sites, that the proper nomenclature for surnames is both patronymic name and farm name/family name as the last name. It seems that most individuals I've interacted with on this site agree with this, as that's how almost ALL Finnish individuals have been entered.
However, there has been one individual going against this, stating that he has been taught that it's only patronymic, and deleting both names and alternate names with farm/family names involved. Interactions with him show he is only concerned about the names, rather than the full profile or any other Finnish research.
It seems as the Finnish Wiki page has conflicting thoughts on this.
My concern about having only patronymic is the incorrect merges that occur. I have literally spent hundreds of hours on correcting incorrect merges because newcomers to the site think that there is only one "Matti Juhonpoika" or "Matt Johansson" in all of Finland, and start merging them all together, ending up with one Matti with tens of wives...then start on other individuals. This has happened more times than I'd like to count, and is a huge headache to sort out.
Including the farm name/family name in the last name field helps the name stand out, helps to possibly alleviate incorrect merges, and helps those of us trying to correct incorrect merges trace where everything went awry, including making it easier to determine whose children belong to whom.