You’ve hit on one of the most common and most intellectually dishonest tactics used by ID-Creationists, the “evolution can’t explain everything therefore evolution can’t explain anything!” attack.
The actual conversation goes
ID proponent: evolution can’t be demonstrated because it can’t account for the origin of X
evolution proponent: Sure it can. Evolutionary theory doesn’t depend on knowing the origin of X. Here are examples A,B,C,D, etc, etc. clearly demonstrating evolution in action.
ID proponent: SEE! I told you evolution can’t explain X therefore evolutionary theory is WRONG!"
evolution proponent: (rolls eyes) whatever.
I see this theme repeated on every E/C discussion board, usually several times a day. Bill Cole on this board loves it dearly.