There's no reason why an update query that doesn't change the file layout and only twiddles some values in place couldn't be made fast with columnar storage.

When you run a read query, there's one phase that determines the offsets where values are stored and another that reads the value at a given offset. For an update query that doesn't change the offsets, you can change the direction from reading the value at an offset to writing a new value to that location instead, and it should be plenty fast.

Parquet libraries just don't seem to consider that use case worth supporting for some reason and expect people to generate an entire new file with mostly the same content instead. Which definitely doesn't have great performance!