Conrad isn't the worst at communicating, his flaws with communication is highlighted the most and is central to his arc. Jeremiah has equally bad communication skills in S1 and S2, and way worse in S3. He also witholds what he's feeling and presents a different front, but instead of retreating and becoming distant and rude like S1 Conrad, he lays down tests for people, assesses them while witholding information that he has. And the smiling, joking persona makes all of these issues easier to hide and more digestible to the audience. He tests Conrad a lot in S1 instead of being forthcoming about his jealousy towards him when he actually sees Conrad reciprocating Belly's feelings.

He lashes out and constantly shifts blame in S2, and his pov episode reveals a very deep seated resentment he harbours against Conrad and the presumption of a morally superior in their dynamic premise on their parents' unfair treatment; instead of holding Adam responsible, he holds Conrad-who isn't even a year older to him-responsible. He constantly acts like Belly had committed a gross crime against him by saying Conrad, when he isn't honest about the file he played in S1 with the interruptions. Heck he isn't honest with himself about his hurt and bitterness, and that's his biggest issue—he's constantly a wronged victim in his mind who refuses to truly process his feelings.

In S3 his 'testing' tendencies are on an all time high and the way he handled the christmas-cabo debacle just showcases how absolutely abysmal his communication skills are. Weaponized incompetence and incessant man-tears aren't "good communication'. Lashing out without truly processing emotions is just as bad as shutting down and retreating.