I’ve had to stick to Audacity 2.10 for years because of essential features removed in later versions. Ex: The “Set Selection Point and Play” option in Preferences > Mouse > Select. It was set to Ctrl + left-click. I’ve no idea how people manage without it. Anytime I have an audio selection and need to listen to a section inside it, I just hold Ctrl and click with the mouse in v2.10. Perfection.
In v2.4 we can’t, since that shortcut doesn’t exist anymore. Now we have to mouse-click first and then hit the Space bar for the audio to start… And we lose our selected segment.
In Audacity 2.4.2 this has been replaced by the more versatile feature “Timeline Quick-Play”.
See: Timeline - Audacity Manual
In short:
Play from a point: Click on the Timeline
Loop Play from a point: Shift + Click on the Timeline
See the manual for other features of Quick-Play.
Even after 10+ years of using Audacity I had no idea this feature existed. Thank you Steve!
It’s not the most obvious feature as there is no menu command for it, but there is a tool-tip if you hover the mouse pointer over the Timeline (time ruler) for a few seconds.
It’s very rare that we remove a feature from Audacity without offering an alternative (usually a “better” alternative, though that can be subjective).
If you find that a feature is missing in a new release, it’s worth looking in the “release announcement” on the Audacity website to see if it mentioned. The release announcement is usually on the home page of the website for a month or two from the release date - after that it can be found in the website “posts” (https://www.audacityteam.org/posts/). If you still don’t find it, then you can always ask, here on the forum 
Or look in the What’s New section in the current Manual with each release - 2.4.2 What’s Hew is here:
https://manual.audacityteam.org/man/new_features_in_this_release.html
There’s always a big link at the top of the Manual’s front page.
Peter