I wouldn't recommend playing her top for a few reasons. Mana issues, performs poorly into fighter matchups, can't pressure tanks, bad splitpushing, and her diving/trade style is remarkably similar to divers like wukong and j4, but they perform extremely well in top lane in a wide variety of matchups. The same can't be said for vi.
She CAN, but her biggest asset is ganking and extremely fast and healthy aoe clearspeed in the jung. Generally you won't be tanky enough for dives or you won't deal enough damage, which is only remedied by getting very fed. Overall though she really can't impact the game when fed as a top laner like she can if she gets fed as the jungler. Her splitpush is weak and she isn't able to pressure a wide variety of objectives (especially if tp is down).
edit: essentially her strengths as a jungler are so pronounced and well defined, while her strengths as a top laner are not that significant and are available in other champions much more suited to top lane. Though she still is technically playable. Think of lee sin top or illaoi/darius/ori support.