What quality can modern factory video editors achieve when resizing?

[Bencuri]

I am still using Sony Vegas 12 with Debugmode Frameserver, just because it is fast enough on my computer and my camcorder is still the one from 2012, so I don't want to change the setup that already works well. But I wonder how much the resizing technology improved over the past decade? The resizing method that some of the members here (many thanks to them) suggested with avisynth works very well. Compared to that, when I resize using Vegas 12 the result is always bad. Blurry image, especially after uploading to Youtube.

Just for curiosity, I wonder how much the factory editors like Vegas improved in this regard, if they did at all? Because back in 2012 they were unbelieveably bad. Maybe avisynth is still ahead of them?

[rgr]

Yes, dedicated upsizers still work much better. Vegas has AI Upscale in its newer versions, but the aiupscale (or nnedi) plugin for Avisynth still works better in my opinion.
Personally, I don't think any upscaler performs well enough to be worth using. It's better to properly process the image at a given resolution and wait for better solutions in the future.