You're saying that those airlines pay you for dropped trips?
Or if you trade into lower value trips?
Or MA's?
Or sick calls if you have no accrued sick time?
Or if you cancel a flight because of a deferrable MEL item?

Quick fact: No, they don't.

Those are caused by the pilot.

If you are removed from a flight because you have a 7 day conflict, or you are approaching a flying hour lookback limit, you still get paid at those other places. If you are removed from a flight because scheduling opted to use a reserve so that the flight wasn't delayed, you still get paid for that flight for it's full value, regardless of what happened with the rest of the sequence.

It's a huge difference.

Seconding this. At 9E, if we get cancelled or reassigned, we get the greater value of the original assignment or the actual flown assignment.

Cancelled, and 12 hours of credit becomes an unscheduled overnight and a 2 hour deadhead? We get paid for 12 hours. Assigned to cover someone else's flying, and 12 hours becomes 15 hours? We get paid for 15 hours.

You have to be either a very senior FO who is about to get displaced to the 145 or possibly ORD reserve in the 175, in which case your days off will be reduced to 11 and min credit of 75 AND you’ll be commuting

Or a very senior captain possibly lifer, either way a new hire will not see something like this, specially if they get the 145.

Do you understand why I gave those specific examples?
Let's go back to what you said.

I'll give you a hint. Those are the only reasons when OT does not go over your monthly guarantee. So it's never "offset by deductions" unless it's caused by the pilot.

A very senior FO would not get displaced to the 145. The very senior FOs have been displacing to the 175, causing all sorts of havoc at the bottom of the 175 CA list.

Yes youre right about that, either way you’d go back to reserve for a while. 11 days off min credit. Or less than 11 days off if u pick up OT

Yes, because you read the wrong part of the contract and don't know what you are talking about. There are 660 pages of company friendly caveats...

I'll give you a hint. Continue reading to the part that says, "If a reserve pilot flies awarded open time on days off and subsequently has a 30-in-7 day conflict in the same calendar month, the amount of flying from which it was necessary to remove the reserve pilot in order to resolve the 30-in-7 day conflict may not be credited above guarantee."

You can lose OT pay if it carries over into the next month and touches a reserve day on your next month's bid and gets recoded as voluntary reserve flying (flying fly free).

I don't think you understand what that part means. If you read it, slowly, you might figure it out.
Think how OT is awarded for reserves, and what restrictions they have. How do you think this situation would occur? Pay close attention to the "same calendar month" part. It's pretty important.