The author first talks about the waste of time that is upfront analysis/planning or adding a buffer for contingency and how Monte Carlo simulation fixes for that, but then the caveats seem to be based on an established team, of a fixed size doing similar style work.
For me, this stage of a project has never faced big hiccups in estimation & our teams are normally quite good at knowing "what's a 2 vs a 5 point story" — if there _is_ a big discussion in a planning meeting at that stage, it's normally because one person has overlooked a key requirement (or the other is assuming a requirement that doesn't exist) so it's a good opportunity to solve for that.
To use the analogy, we're probably quite good in established teams at estimating how long it'll take to write 10 blog posts. The trouble comes when someone says "The latest blog posts aren't generating enough interest. Can you estimate how long it'd take for you to write 10 poems instead? We want a mix of iambic pentameter and maybe some trochaic tetrameter (TBC). We've gotten budget approval to increase the size of the team, so we'll have 5 new people (off-shore) joining next week so we can go faster. Also, some of the old blog posts seem to be getting lots of visitors in South America, so we may need to translate these to Portuguese/Spanish too. When can you give me an estimate for all that?"