Bottleneck at the DB/network is BS. Cheap AWS boxes have 200Mbps of throughout and you'll basically never get that out of any of the slower languages on a box with something like 1VCPU 1GB ram. Slightly more expensive boxes have 1 gigabit which is hitting many thousands of HTTP requests per second, even Java/Go struggle with that load.
I have seen MS SQL server handle over 10k database queries per second on a regular machine in a real, huge application (over a million lines). Can Python handle 10k queries per second? Definitely not. In Java or go that load could probably be handled by a single AWS box that costs $10 a month.
I have never seen a database maxed out that wasn't stuck because of table locks. I've seen applications like WordPress die at 10, requests a second
There's more to bottlenecks than throughput. Latency also needs to be considered. A 5MB webpage will load much faster when served from a 100Mbit connection with 10ms of latency, than a 1000Mbit connection with 300ms of latency. Especially when you consider that web page requests (pre-HTTP/2) consisted of many separate requests to fetch all the different assets (e.g. CSS, JS, images, etc).
Secondly, the majority of websites that make up the Internet (and Intranets) are not serving 10k/second. They're serving a 100th of that.
Third, because your database can handle 10k queries, and your database can aggregate and manipulate data, and it's optimised to do this -- it might be a good idea to perform these functions at the DB-level, as opposed to the web application.
Finally, as stated previously, for most businesses, it's easier to buy more beefy servers, or get a more experienced PHP dev (that understands how to optimise code) than it is to find a Go programmer.
I have seen MS SQL server handle over 10k database queries per second on a regular machine in a real, huge application (over a million lines). Can Python handle 10k queries per second? Definitely not. In Java or go that load could probably be handled by a single AWS box that costs $10 a month.
I have never seen a database maxed out that wasn't stuck because of table locks. I've seen applications like WordPress die at 10, requests a second