There's really not a ton of truly bad teams this year it seems like compared to other years. And of the actual bad teams record-wise we have a lot of games left against them
CWS - 4/4 remaining
Detroit - 3/3 remaining
KC - 3/3 remaining
Oakland - 0/3 remaining
Washington - 3/7 remaining
St Louis - 10/13 remaining
Colorado - 6/6 remaining
That's every team more than 4 games under .500 right now, and of the 41 games against those teams on the schedule, we've only played 10 of them so far. Only 2 more of those games will be played between now and July 16th which is roughly the deadline for the Cubs picking a lane in terms of buying or selling. 29 of "easier games" will be played after that date (13 straight games against those teams begin on July 17).
Like you pointed out, it doesn't mean the Cubs are magically good because their schedule has been tougher, but if 29 of their 41 easiest games came before any trade deadline decisions needed to be made instead of after, there's a chance we'd be in a better position to buy.
*Also just a caveat that its still possible the Pirates are actually not that good and by the end of the season they may be grouped into the bad teams.