I noticed the same thing during the autopsy of a buddy's ARF awhile back. Truth is, I can't remember being able to see the insides of many ARF wings to know whether or not it's a common practice with the ARF factories.

But what I noticed was that the wood also happened to be quarter grain. That's a perfectly good choice for webbing and the type of grain in this case made the choice perfectly acceptable. BTW, that wing didn't have webbing full span and most planes don't need full span anyway.

I wouldn't worry too much that the webbing grain is or isn't oriented the optimum direction. ARFs have other wood selection problems that're significant. The direction of the grain in webbing really depends on the wood itself more than the grain direction as to whether or not the piece will be up to the task. Because if the web touches at all 4 sides, it'll probably be strong enough to resist the compression at mid-bay. That is, if the web is appropriately glued.

There are lots of choices that matter as much as the direction of the grain. Is it attached all around. Is it thick enough. Is it flawed wood. It's certainly true that if we were building our own models, lot's of choices would be made with better understanding. But not all of them have fatal consequences. I'm worried a lot more by the design choice of liteply in firewalls and wing hold-down tabs/bulkheads.