My personal, anecdotal experience is that many of the minions in 1.4 no longer properly attack bosses. The entire reason I gave up with my summoner, in just NORMAL MODE, is because the majority of the minions I used wouldn't stick to the boss and attack it like they used to, so my DPS was completely shot to pieces. I ended up fighting Duke Fishron as a Challenge-Run No Armor or Damage Accessories ranger because my sharknadoes refused to attack him. The laughable solution to this is to get in kissing distance of the likes of Fishron, the Empress of Light, every single hardmode boss and *whip it*. Yeah, no.
1.4 took the class with the absolute least defence, and the absolute least mobility (because just to be a summoner in later Hardmode you end up giving up accessory slots as well, and your armour gives no help), and told it that it had to melee. Not all players are even as good as Chippy, and Chippy reckons he's garbage. In amongst this ever increasing pandering to the lunatic hardcore players, everyone apparently forgot that many people are on phones, casual, or just plain freaking old and ain't exactly the twitcheroo they used to be.
I gave up on Summoner, and started a melee run in disgust instead (I like the journey, so I start over in situations like this). When I got back to Duke Fishron, I handed him his butthole on the first try, because my melee actually had MORE RANGE than the summoner and stupid amounts of defence and helpful accessories compared to the summoner and her lazy minions.
Summoners have MASSIVELY overtuned disadvantages put in place because the power of minions is enormously overrated. They have no defence because, theoretically, they should spend the entire time running like hell away from danger while their minions kill stuff. But they've been given whips and minions that are reticent to act if you're not using the whip. They have to give up accessory slots to continue adding minions and actually just be a summoner, which further impacts their mobility, personal combat abilities, and survivability.
The devs seem to have this idea in their head that summoners can effortlessly run away from everything while the minions slaughter it all.....but that's not the reality in the game. Bosses that want to get close to you will do so. Events will throw enough at you that you're going to get hit a lot regardless. Even with fully functional, bloodthirsty pets the summoner has still been more challenging than the cookie cutter classes. Summoners have always been the glassiest cannon in the game, and they didn't even have THAT BIG of a cannon. Now they have to take their glass face and headbutt bosses to even get their cannon to fire.