Under the old system, the best way to gain skills would be to only attack at point blank. Attacking stuff at range was a very suboptimal way to gain skills.
The new system requires far more xp to gain levels, but compensates for it by increasing skill gain based on distance. Meaning that the xp gain isn’t maximized at point blank, but at the longest range you can keep scoring good enough hits.
Also, you need more perception to keep improving skills with inaccurate weapons.
Archery is relatively badly implemented at the moment and needing to use the blowgun wasn’t intended. I don’t recall anyone describing a good solution to this, though.
Self-bow was supposed to be the archery training weapon, but under the current system it doesn’t work. Self-bow was never properly implemented though, so the blowgun is actually a step forward here. Both of those should probably be removed and short bow should be enabled earlier.