I think that the point that commenter was trying to make was that when you try to move people onto a wiki – which is better than email for certain types of work – you do need to be very active in encouraging people to use the wiki instead of email.
Here’s an example: Let’s say someone emails you to ask for a bit of information that you think might also be of use to other people in your team. Instead of replying by email, you reply on the wiki and then send an email with the URL to your colleague. That way, you both can encourage your colleague to becomes familiar with the wiki, and you can ensure that the information is available to anyone else who needs it.
People don’t adopt new tools if they think they can carry on using the old ones, and they frequently need this sort of encouragement to migrate their work processes to the new tool. It may need a bit more effort in the short term, but it all works out in the long term.