Sure, but that's beside the point.
Text based graphics with fancy or custom fonts is just crazy efficient. That is exactly how we got the amazing graphics of The Last Ninja or Turrican on machines with less than 64KiB useable RAM.
Same for more modern embedded devices. If you constrain yourself to text you increase both runtime performance and your developer productivity.
Are you claiming that scrapping together boxes and whatnot with line drawing characters is more efficient than just drawing the lines directly?
The same isn't true for modern embedded devices, they don't have tile rendering hardware. If you connect a i2c/SPI screen (SSD1306, ST7735), you write all the pixels on the screen (or pixels to some subregion of the screen), these screens do have a backing memory in them.
So in order to draw a line, you will - objectively - have to copy/move more bytes if you approximate line with character symbols.
This isn't a big deal, but crazy efficient it is not.
All the efficiency when drawing on those screens mostly relies on how well you chain together DMA transfers to portions of the screen you want stuff to be drawn to, so that SPI transfers aren't blocking the CPU (that's assuming you don't have memory for a second full-screen buffer).
It was crazy efficient on character or tile-based hardware. It makes no difference on bitmap displays, or rather adds some overhead.