Both of these tools, Selenium and JMeter, are useful for different purposes.
As mentioned on the Selenium website:
Selenium automates browsers. That's it! Primarily, it is for automating web applications for testing purposes.
In other words, it's used to validate user behavior and testing of end-to-end functional scenarios in the browser. This is the primary purpose. Yes, people use Selenium for other purposes like web scrapping, but these are seen as secondary uses. "Performance testing" using Selenium is not the same as using JMeter; this is meant to read as "how fast can you perform UI tests for a single user." You cannot use Selenium to simulate heavy load, web traffic, 100's or 1000's of users at a time.
As mentioned on the JMeter website:
Apache JMeter may be used to test performance both on static and dynamic resources, Web dynamic applications. It can be used to simulate a heavy load on a server, group of servers, network or object to test its strength or to analyze overall performance under different load types.
In other words, the primary purpose with JMeter is as a load and performance testing tool. While it has expanded to other types of testing, load and performance is it's primary purpose.
What's your main purpose?
If it's front-end/UI web app functional behavior and validation, go with Selenium.
If it's load and performance testing, anything at the web socket layer, go with JMeter.
Note: OP's question and quote seems to relate to this article: https://www.blazemeter.com/blog/selenium-vs-jmeter-which-one-should-you-choose-and-when/
This article goes on to say:
Can Selenium do everything that JMeter does?
No. Selenium can be used for some performance testing (e.g. limited
bandwidth testing), but it cannot be used to load test with accuracy
Can JMeter do everything that Selenium does?
No. JMeter can record detailed web sessions originated by web browser
applications and replay the web session as the server sees them.
However, each replay does not reproduce client side elaboration (e.g.
is focused on how a web page is presented to a user, Selenium is a
Can JMeter and Selenium collaborate?
Yes. There are various situations where both tools can sync on the
same testing application.
The record and replay in JMeter is similar to using Selenium IDE browser extension.