You must be young. The gap between 1989 and 1999 in computer terms is inmense, far more than the gap between 2010 and 2020. You could emulate a 1989 m68k Mac/Amiga on a Pentium 3 from 1999, for example with BasiliskII/UAE.
Performance increase did not stop; smaller, better designs. The exponential is just a bit lower.
We don't realize it, just as someone using a text terminal may have not realised it between 1985 and 1995, if every response after a key press was already instant.
For typical GUI interfaces, tasks like tossing video data around, and so on, computers became approximately inifinitely fast sometime c. 2005 - 2010.
