The point is, a big-tax, big-spend Dem who takes tax exemptions is stealing from the poor by their own logic, and from eveyone else by ours.
There are two reasons for pointing out their logical inconsistencies, neither having to do with the elites of either major party.
Reason #1 is to make a logical appeal to those rank-and-file Democrats not yet so stultified and emotionalized that they are allergic to logic.
Reason #2 is to remind our own rank-and-file that Republicans take logical consistency seriously, and to innoculate ourselves against the types of emotional fetishes that plague the Democrats.
You are too young to remember the good old days, when marginal rates were high, and not indexed for inflation, so one had bracket creep. Thus the Feds had lots of money, and handed it out through specialized tax breaks and loopholes. This had two advantages. First, the Dems could regulate behavior through giving tax breaks for certain kinds of preferred behavior, and second, they could buy votes, and/or anneal to themselves the loyalty of groups that might otherwise stray. The system worked well, and we had a stable Congressional government, of, by and for the Dems.
And then tax brackets were indexed for inflation, and the marginal rates went down, and slowly the glue holding it all together decayed, and then finally snaped.
And now we have the fractious Congress of today, with little civility, and everyone out for themselves. That is what happens when you don't just let the Dems run things.