Flush fingerboards are interesting. Not necessarily for every player...I'll explain a few reasons why.
First of all, it is my opinion that many players press the string to the fret much too hard in the first place so the spruce as the fingerboard for the upper frets is not the only place they need to hold back.
Often the frets are set in an ebony or other hardwood piece which is then inset into the soundboard. These ebony inverts can be seen in the Lete guitar played by Anna Kowalska in another post up for discussion at the moment. These inserts protect the soundboard somewhat and give a stable base for the fret.
Often the soundboards of the early guitar were not finished beyond a light wax or perhaps oil/varnish finish. That part of the fingerboard can get dirty but in actual fact much of the repertoire doesn't spend as much time in the higher frets as we would imagine so it doesn't generally get that soiled or damaged.
Flush fingerboards are kind of a holdover from the Baroque guitar era. They work well for non nail players as the strings are a fair bit closer to the sound board than the raised fingerboard version. This closeness to the soundboard can be an issue for players who maintain longish nails...they tend to make contact with the soundboard more than is desirable. This is one of the reasons thought to be instrumental in the acceptance of the raised fingerboard. Players playing with nails needed more room. There are other important structural and acoustic reasons for the move to raised fingerboards as well. Those with raised fingerboards tend to be louder with a fuller tone.
Annas technique is very appropriate for the instrument. She is a highly accomplished lute player so she is accustomed to having the right pinky planted (easier on a flush rather than a raised fingerboard), playing with no nails and at a hand angle slightly reminiscent of lute right hand technique. She is probably my favourite player of early instruments and is a perfect example for my argument that the 19th century guitar, especially the later ones, are absolutely appropriate for much of the 20th century repertoire and not just quaint relics of a long gone era.
Scot Tremblay Guitars
"One picture is worth a thousand words. So, for me, one good note put where it should be put, will say what it will take some people many notes to say. ~B.B. King, 1986