Can you explain this comment? What are people doing that you believe is unintended?
The actual game which is sold, as the designers intended, has a lot of optional rules in it.
Most of the game is optional rules, which are only supposed to be added to the game at the discretion of the DM. Feats and multi-classing are the obvious ones, but even individual classes and sub-classes are only supposed to be available at the discretion of the DM.
The main reason that they did this is because they couldn't be bothered to balance everything against everything else, so they only did a quick pass over some of the classes and races, and then slapped a warning label on the rest of it that it's up to the individual DM to decide what's appropriate for their own game. (It's hard to say why they thought that was a reasonable burden to put on individual DMs, but my best guess is that there was external pressure to release on some sort of schedule.) While that may seem like a cop out, at least they warned us.
Whenever someone complains about paladin+warlock, or battlemaster+sharpshooter, or cleric+goodberry, what they're really doing is complaining that their DM didn't spot a problem in time to intervene; or otherwise felt compelled to
not intervene, regardless of what the game makes clear is their job.
If two specific feats are ruining your game, then
some of the blame goes to the DM. The feats were never part of their game in the first place, until they specifically decided to add them. They made a bad decision. Even though a lot of blame also goes to the designers, for putting the DM in the situation where nothing was balanced or playtested, the DM was still the one who chose to go forward like that.