Short answer: Yes
Long answer: Depends
Certain metals I personally don't have equipment to weld, but I have connections to people who do and could complete said task. Certain metals I have never had the opportunity to try. I will tell you plain and simple weather I can or can't do something. Altogether I will still give you someone who can.
I have 6 Years of welding experience so far and counting. Two of these years were through schooling. I have done many kinds of tests; Stick, Mig, Tig, Combo, Pipe. During this time attending multiple welding competitions and placing top 5. Aside from schooling I have experienced the test of time and know good from bad welds. I have seen welds fail and why. If its not done properly then it will fail.
Typically when asked this question, there is two outcomes. Yes I may be able to weld said thing, but more than likely it's cheaply made and better to just buy again. On the other hand it ends up being not so quick. All in all I will never judge, some just need someone to give them an answer and it never hurts to ask.