Er, no - you can position at a floating point position for the first tile - the others are added at a position that is exact - just add the texture size and they will line-up ok.
The other point is, modern graphics cards are all 3d-based so you have to think (and optimize) in those terms - every square of graphical data is 2 triangles in a 3d world.
Modern 3d hardware has no problems with huge textures - but for older 3d hardware the inital limit was 256 X 256. To see the difference in speed that droping texture size and tiling has on a poor graphics card will convince you to adopt it - you just can't think in 2d terms!
The other point is, modern graphics cards are all 3d-based so you have to think (and optimize) in those terms - every square of graphical data is 2 triangles in a 3d world.
Modern 3d hardware has no problems with huge textures - but for older 3d hardware the inital limit was 256 X 256. To see the difference in speed that droping texture size and tiling has on a poor graphics card will convince you to adopt it - you just can't think in 2d terms!