I agree that not having a natural flow of control is more prone programming debugging. However, he does say things that are wrong, ex: "It's impossible to slow down the pace of accepting new incoming client connections." You can slow down the pace by doing the following:

     const http = require('http');
     let count = 0;
     const THRESHOLD = 1;
     const server = http.createServer((req, res) => {
       if (count++ < THRESHOLD) {
         // do work
         res.write('success');
         res.end();
         setTimeout(() => count--, 10 * 1000);
       } else {
         res.write('limit');
         res.end();
         count--;
       }
     });
     server.listen(10000);