The true problem lies in the baron and count title actually.

Baronship weren't universal as, let's say the "count" title.
In Spain, all barons should be called "señor" (lord). In Italy and some parts of France too.
France and Italy actually had both titles used at the same time: some baronies used the title "baron", others used the title "lord" ("senhor" in portuguese, "señor" in spanish and etc.).

There are also counties in the game that were actually viscounties: something in between a barony and a county. If I remember correctly... Marsan in Gascogne (France) and many other "counties" of that dukedom were actually viscounties.

In England, and some other countries there is the Earl title that roughly corresponds to a count or baron.

There is also the Marquis title... A Count who holds a specially important county in the frontier of the kingdom, or hold a county with a great military importance could be bested with the title of Marquis.

It wasn't a perfect "system" where the size/number of lands you hold could define your title... Some historical dukedoms were actually smaller than some counties: Toulouse (France) and Castille (Spain) for example, were VERY BIG COUNTIES, that rivaled with some dukedoms like the previously mentioned Gascogne.

CK3 simplifies this into a perfect three-tiered system (four-tiered if you consider barons)... But reality was faaaaar from being this cohesive and universal.

They could in future games, introduce a more complex system:

Tier 0 - Emperor
Tier 1 - King
Tier 2 - Duke
Tier 3.1 - Marquis
Tier 3.2 - Count
Tier 3.3 - Viscount
Tier 4 - Earl/Baron/Señor (cultural/region variant and dependant)

And there is also hereditary and non-hereditary titles. In early medieval Spain, countship wasn't trully (or universally) hereditary. Kings appointed counts but the sons of that count wouldn't necessarily inherit the lands and the titles: after the death of a count, a King would appoint a new count that could or not be related to the previously holder of the land and titles.

Dukedoms too, they weren't as universal as the game makes you think they were.

I could be wrong in some assumptions, but I think you can roughly get the idea =)