Some ideas that come to mind:

  - Concentration of power/attention/market share/etc. can lead to abuse
  - Competing ecosystems push each to get better
  - Different tools can be good at solving different problems (e.g. different LLMs may be good as solving different tasks)
  - Allows people to use tools they're more comfortable with (e.g. worked at one company where everyone was forced to use vim, needless to say I didn't want to stay there long)