The .7z extension is a staple in the gaming and emulation communities for a few reasons:

Knowing the software you're using can help troubleshoot the issue.

Most modern tools, including WinZip and various emulators, can now open or at least read the content of these archives directly.

In a standard ZIP, each file is compressed individually. In a "solid" 7z archive, all files are treated as one massive data block.

For massive ROM sets or game assets, the space savings compared to ZIP can be measured in gigabytes.

The .7z format, created by 7-Zip , uses a method called to achieve much smaller file sizes than traditional formats like ZIP.

Unlike some proprietary formats, 7-Zip is open-source and widely considered safe for distributing large software packages.

The "catch" with solid archives is that if you want to extract just one small file from the middle of a huge archive, your computer might have to process the entire block before it can "find" that specific file. Additionally, if a solid archive is corrupted, you might lose every file in that block rather than just one. Why You See It Everywhere (Especially Games)