That's an extremely interesting question. The nature of the Turkic verb (not only Turkish) and, more generally, the nature of the Turkic predicativity poses really many conceptual questions. Since the Turkish nouns as well as qualitative adjectives can also be predicates that are marked for person and tense, the question is where to draw the line between them on one side and the verbs on the other.
A similar situation is found in other languages of what is called the Altaic macrofamily — in the Tungusic languages (like Manchu), and to a lesser degree in Japanese. Both Manchu and Japanese have no category of person, so only tense is marked on their verbs
In Japanese, the verb in the nonpast tense can also be used as an attribute, in a manner adjectives are used:
男は書く。Otoko wa kaku. — man NOM write/s — “A man writes.”
書く男 kaku otoko — write/s man — “writing man / man who writes”
In Manchu, the verb system is organized in such a way that one can easily get an impression that there is only one true verb, “to be”, which accidentally is bi in Manchu. This bi is the only verb in the whole language that has the indicative mood form, it is in the present tense. There are numerous classes of participles which have tenses and can serve as predicates, but still they are nominals, they all can be used as attributes, too. Bi is added to the nominals to make them finite. The thing is, Manchu allows both finite and non-finite sentences, the latter ones being sentences without mood expressed, that is, showing the situation as objective, while by adding finiteness which is inseparable from the indicative mood, one adds a touch of one's own subjective evaluation of the situation as real.
All of such examples of languages where finite verbs can be attributes (Japanese) or where one can choose between saying things finitely or non-finitely (Manchu), or where nouns can be finite (Turkish) demonstrate very different faces of finiteness. The three languages are Altaic and irrespective of whether they are really genetically kindred (let us call it Sprachbund), they have very much in common, especially in grammar. But such a variation in the idea of the finite verb as we can see it in the 3 languages suggests it is an innovation in each of them as related to what there might have been in the times when they were still in contact. My personal point of view is that the participles eventually acquired finite meaning in those languages, but it can well be the other way round that finites degraded into participles and then later again became finite with the rise of the category of person as in Turkish. Anyhow, all those processes happened millennia ago and are pretty hard to be traced back.