The same happened to music when digital music production at home became more accessible. The hard part is separating the wheat from the ever growing larger share of chaff.
Quantity has a quality (or lack thereof) all its own.
How many shit books can or will you wade through to find a good one? Particularly when some percentage of the shit ones are "good enough" that you won't necessarily know it was shit until after you've read some or all of it? What do you do when the ratio of shit to good is 100:1 or 10,000:1? In the past, you could find a trusted publisher or reviewer without too much trouble. Soon, if not already, the publisher and the reviewers will have the same dross ratio as the books do.
You need to do mid-frame tile updates just to show a full bitmap frame. There’s 360 8x8 tiles on the screen, but the tile indices are 8 bit (you can only reference 256 tiles). You can store only 384 tiles in VRAM - a bit more than a full screen. So the mid-screen update is to go from one tile dictionary to the other, so you can access 360 tiles in total.
You can update 1 tile per scan line (during hblank), so 154 tiles per frame (including 10 vblank scanlines). So you need 2.5 frames to replace all tiles.
If you are really smart about updates, you can “race the beam”, basically start updating tiles just as the frame starts rendering, just behind the active scan line. Then you can update maybe 280 tiles before the active scan line of the next frame catches up with you.
