webOS in 2009 isn't even a comparison for a few important reasons.
* They were primarily RAM restricted at only 256mb.
* The then new v8 engine was about 4x slower than the current iteration (not to mention using much more RAM). Webkit is also much, much faster today
* They used QtWebkit -- a slow and grossly outdated version of webkit that offered bad performance even back then.
* There team seemed to have zero experience in actually using and optimizing a Linux OS.
A single-core 1GHz A5 chip was a crazy idea. The ZTE Open C came out 6 months later *at the same price8 and had a better screen (480x800 instead of 320x480), twice the RAM (512mb instead of 256mb), and probably close to 4x the CPU power (2x A7@1.2GHz instead of 1x A5@1GHz -- for reference, AMD runs an A5 as their security coprocessor on their x86 chips).
The ZTE Open was simply a mistake. It would have been a mistake no matter the OS or native vs web apps.