From my personal experience across several different Realtek and Intel LAN adapters, Intel has had higher performance, and usually does not break with a driver update. Realtek on the other hand, has worse performance at best. Sure you could say that maybe it's just my network setup that's "built different", but I have also been to other friends' houses and helped them with their PC setups too; it's not just my setup, Intel's LAN adapters are just better because they have are always downloadable from Intel's website, whereas with Realtek adapters, usually you are supposed to use the one that is on your motherboard's support page, and I believe this is where the issue stems from. Since you always have customized drivers from the motherboard manufacturers, every manufacturer is making custom driver changes, that increases the variability of successful operation with all Realtek adapters. Not to mention Intel's LAN adapters have much more [useful] settings than Realtek.
Now back on topic, I have no experience with MediaTek, and I have not heard of that company prior to reading this article. RANT: I mean AMD really could just use Intel's LAN adapters and not be stubborn about it but, okay I guess they want to do their best to ensure competition even if it means the consumers will have a shit experience, as was the case with the infamous USB dropout on Ryzen, and I bet you they even will attempt to deny all allegations of LAN problems at the beginning of the launch.
Have you installed the from the motherboard manufacturer? Or from Intel? Also check your wifi card's antenna connections (internal and external), even a loose connection will cause problems, and in most cases it's a loose connection on the internal side.
And with that statement, you are trying to set the law of the land. Not everyone's experience is the same as yours, it is absolutely possible that you had a seamless experience while someone else who did everything right is having problems left and right. Because there are logic components on a wifi card, yes there can be faulty cards as well. I could go on and on, but unless you can prove that every single product made by Realtek is free from defects (100% not true btw), you can't just state that and try to write it in stone.
Why not just have consistent performance from the beginning then? Why would you have to wait years to finally get better performance than its competitor (generalized statement)? There are multiple ways to look at this of course, but from my viewpoint, AMD has a lot of untapped performance on their GPUs because they don't have optimizations from the start. Personally I will never get an AMD GPU as their GPU encoder is straight trash for streaming, but that's a niche thing I guess...