I'm just the weekend warrior type rider but I ride my carbon road bike about 15mph on average, including climbing and downhills. That's wearing typical biking clothing doesn't include any extra weight in clothing or otherwise outside of two water bottles. So 100 km is about 4 hours. And that's actual moving time. 4 Hours is a long time without a break out of the saddle.

I get on my touring bike and that drops to about 13 mph with winter clothes but no extra weight other than a bar bag, rear rack and the water bottles. If I were commuting that distance, I'd need some extra clothing and shoes to change into when arriving, something to "freshen up" with, and may need some work materials i.e. computer, files, paperwork, etc. so I'd need that extra weight in a pannier and now I'm adding even more weight.

So now I'm getting up towards 5 hours commuting time. Again, that's actual moving time, not factoring in breaks.

My point is riding 100km for a fun vs commuting 100km for work wouldn't be the same ride. At least not for me.