The phrase "always functioned as a" is correct and usable in written English.
It can be used to describe a consistent role or purpose that something has served over time.
Example: "Throughout its history, the library has always functioned as a community hub for learning and engagement."
Alternatives: "has consistently served as a" or "has always acted as a".
Although it has always functioned as a working station, the place fell into disrepair.
In Ireland, the pub has always functioned as a home away from home for the entire family.
And the royal family has always functioned as a symbol of national unity, where there are few obvious others (even Tintin is controversial these days).
For Mr. Halbertal, like for the vast majority of Israelis, the army is an especially sensitive institution because it has always functioned as a social cauldron, throwing together people from all walks of life and scores of ethnic and national backgrounds, and helping form them into a cohesive society with social networks that carry on throughout their lives.
Mexico City has always functioned as a safe haven for journalists.
By positioning himself as a trailblazer for the free culture movement, Girl Talk's music has always functioned as a political statement, whether he frames it that way or not.
New York, after all, has always functioned as an incubator for new businesses that move to new locations as they grow.
Summer is two years my senior, but I've always functioned as an older brother.
Perhaps the work of artists have always functioned as an extension of themselves, the art directly tapping into the artist's interior, previously undisclosed personhood.
Drones aren't harbingers of the singularity, they aren't all armed with missiles, and they don't always function as seamlessly as we'd like to believe (or worry).
The functional role of Sec proteins in neurons, however, including whether they always function as a canonical octomeric complex, remains unclear.
