Not necessarily. VGA mode 0x13 is just a single screen of chunky pixels, and as you may know some really nice PC platformers use this mode smoothly and without jerkiness. The same goes for the C64. There is only 8-pixel scrolling and a lot of smooth platformers obviously run on this, too. No changing of viewports (well, on the C64 there actually is to some extent but only in terms of screens, not pixels), just copying new data into video RAM. These are both proven "reasonable" platforms for 2D scrolling.
There are a lot of smooth and technically superior platformers on modern PC's too. One problem is that it's hard to do everything in time when there are a bunch of other tasks running on the PC. It's not necessarily a problem if you have a fast enough computer, but since most classic Amiga games don't have to share resources with other tasks, looking at the good old, tightly coded DOS games is a lot more fair.
Very true. There was also the somewhat undocumented (320x240) VGA "Mode X" which allowed page flipping. Anything I wrote I used 0x13H because it was just simpler to deal with. Also 320x200 fits in 64K which worked out better with the PC's then horrible 64k segment/offset type architecture.
http://en.wikipedia.org/wiki/Mode_Xactually, if you'd like to check out a awesome modern platformer, check out Trine
http://trine-thegame.com/site/I ended up getting both the PS3 and the PC version I liked it so much.
