Draytek is still mostly using quite old MIPS processors, these days owned ny MaxLinear, prior to that by Intel and originally by Lantiq. Some of this obviously has to do with the xDSL capabilities, since the chips in question have good xDSL support.
However, the SoCs were originally launched as far back as 2014, with some being from 2017, since Intel didn't invest too heavily into new SoC designs due to them pushing to sell Atom based router chips. However, the latter backfired, as Intel has some major hardware bugs in those platforms and based on what I know, most of them were never manufactured.
So what you're looking at is 600MHz to 1GHz dual core chips, albeit with a faster network engine. They're capable up to a point, MIPS processors are good for routing data compared to Arm based processors, but they're not as good when it comes to technically everything else.
It seems like they're using MTK in some of their non xDSL products, but it's still MIPS based processors from 5+ years ago.
Obviously in your case, you don't need the WiFi end of the router, but Draytek is way behind here compared to the competition, most likely because they have to spend a lot of time to make the WiFi drivers work on their platform, since not only are MIPS and Arm Linux different enough to require the drivers to be recompiled, but as there's obviously going to be some work to integrate everything into their own custom OS, although this mostly applies to all router manufacturers.
I'm not saying Draytek are making bad products as such, they are after all known for making very stable products, but they are behind the competition if you start comparing things like VPN throughput, WiFi performance and options, as well as many other things.
If you like them and if the performance is good enough for your needs, there's no real reason not to buy their products, if you keep the limitations in mind. Unlike say TP-Link and several other of their competitors, they do seem to provide better software/firmware support, which is a bonus.
A bonus with the Asus, is that Merlin supports it. And it was the 68, not 86 that I linked to
www.asuswrt-merlin.net
One last thing, if you get a router with WiFi and decide not to use the integrate WiFi, please attach the antennas regardless, as you can fry the WiFi power amplifiers if you power on a router without the antennas attached.