Where do people get the impression that Russian army is strong and capable is beyond me, they just throw people into the meat grinder and sit on top of the infinite Soviet arsenal of old equipment.
"Quantity has a quality all its own". They aren't considered "strong" because individual Russian battalions are expert warfighters per se. They're considered "strong" because the Russian military-industrial complex in its totality is not something that can be idly ignored by anyone except maybe the US or China.
Basically Russia scores high on 3 particular Principles of War: Mass, Offensive, and Simplicity. Not so well on the other 6 though.
https://www.trngcmd.marines.mil/Portals/207/Docs/TBS/B2B2269...
Frustrating to watch.
There are also larger issues to consider beyond just "we want the help the Ukrainians". The best stuff we can send has a bunch of sensitive NATO/US technical information (radio comms, etc.). Do we want to risk that gear falling into Russian hands (and by extension probably getting shared with China)? If the answer is "no", we either have to send alternatives or send the equipment to depot maintenance areas to have the sensitive tech removed. That takes time.
Do we want to risk escalating the war outside of Ukraine, if the Russians respond kinetically to armaments shipments? The answer is again an emphatic "no" from almost every nation except maybe Poland.
Hence the popular snarky refrain: "NATO will fight Russia to the last drop of Ukrainian blood". Western governments and people will "stand with Ukraine" as long as it doesn't involve them really risking anything (such as themselves being on the receiving end of Russian missiles or artillery).
More concerning (imo) is gear, particularly man portable anti-air weapons, sold to terrorist groups either via corruption in the Ukrainian forces, or a Russian op to supply NATO arms to such groups.
They seem to be doing quite well against the modern army of Ukraine, NATO-trained for 7-8 years now.