The web works better when site designers try to exert less control over it. Who are you to tell me how wide my browser window should be?

https://simpleanalytics.io/simpleanalytics.io

Most of those visitors are likely coming from HN, a community of people who are more likely than most to have multiple monitors. For the record, I multi-monitor at all my stationary worksites. But I don't carry external monitors on planes, airports, coffee shops, etc.