There are a number of reasons why I introduced the term 'Ür-Tarot' - but essentially to be able to refer to its un-manifest impulse not from some time past, but rather as the spiritual archetypal impulse embedding itself is the creation of various Tarot decks via the artistic creative means of designing artists and craftspeople.
Yet, still looking at the various renditions, one may very well reflect as to what of the given decks is Tarot, and what are additions to Tarot. In that sense, I personally consider that the Sola Busca influenced imagery in the pips of the WCS-type decks are non-Tarot additions. Of course, if someone considers that the Sola Busca is itself a Tarot, then we shall simply disagree.
With regards to the Visconti, a number of elements preclude it from, in my personal opinion, being a close reflection of the Ür-Tarot. The first and foremost is the likelihood that it does not comprise the requisite number of images in its Atouts (ie, 14, expanded to 20). This is not to necessarily deny that it could even have been influential, and be one of the highly important influences, on the later emergence of Tarot (if one tends to view the Visconti as historically earlier, which current historical finds suggest).
Nonetheless, the Visconti decks, however beautiful and significant they may indeed be, are not Tarot, any more than the Sola Busca, or the Mantegna decks.
With reference to whether Mark Filipas's work is erroneous or not, this would not 'prove' any point other than Mark Filipas is erroneous.
Tarot has many strands and influences that weaves itself into the small filaments extending themselves from the roots of the foundation of the Tarot tree.
My personal current view is that a number of pre-Tarot-emergent influences weave themselves into what we finally recognise as Tarot. Of these, the various religious and cultural expulsions and repressions during the 3 centuries prior to the first instance in which we have found the word 'Taraux' speak of various needs to be careful as to what was then outwardly presented, and what its possible genuine uses were.
The reference I gave in another post as to the crypto-Jewish usage of cards and 'gaming' on the Sabbat in order to still be able to relay the various important reflections without arousing suspicion may have been part of what was at play.
It is also interesting that even the Tarocchi in Italy emerges only following (and not long after) that great Jewish exodus from Spanish lands in 1492. Of course, it was not only towards Italy and the adjacent franco-italian islands towards which the exodus took place, but also in existing crypto-communities in which were relatives in the Provence, Burgundy, Lyon, and Languedoc general areas...
I realise that I may have in some ways moved away from the principal discussion of the Visconti and the Marseille - yet my previous paragraph may also hint at other discussions that have taken place on Aeclectic (and of course elsewhere).
Let's perhaps look at one possibility - and of course no historical materials, to my knowledge, yet do this full justice, even if there is some circumstantial partial evidence.
What would a community that considered its own culture of high importance do in order to be able to pass on the same - in terms of its language, its allegories, and its regulations - to its younger members without risking life? one means is precisely what evidence has already uncovered: Crypto-Jews played cards on the Sabat, and told, in reality, stories.
Another is how to teach not only words, but have a means of recalling and remembering both the AlefBeit and important Hebrew words. Here is where Mark Filipas's uncovering of a correlation becomes highly important. Could he be incorrect? I suspect that as it is my claim, which is far stronger than his, for Hebrew inclusion into the Marseille, and into the Atouts's increase to twenty-two (and therefore into making the deck a Tarot) deck, it is I who may be incorrect - Mark only points to there being a significant number of words seemingly reflected in the imagery.
...but why include, then, the pips and courts? initially, perhaps for no other reason than for the appearance of a game. But even then its internal structure becomes important material for exegesis!
The Visconti does not contain the same proportion of cards - though I do not doubt in the least that its allegorical elements is also of high and significant importance. Neither do other decks - though they too include numerous, esoteric, and allegorically rich elements (and I of course include the WCS and the Mantegna, amongst numerous others, in this wonderful richness).
The Boierdo poem, and other decks that perhaps (as is argued by some) even arise prior to the Marseille, also incorporate important elements, and contribute to further reflections of important significance for understanding more deeply Tarot. As reflections of an Ür-Tarot, however, in what ways to any other deck come as close?
Notwithstanding this, the artist, imbued with the tradition of the tarot, painted a tarot deck.