What you're seeing stems from my earlier statement of "apples to oranges".
Shield coverage is a flat number. It has a surface area. You can't make it any bigger. You can re-position it, you can shift your body behind it, you can swap between a strap or a punch to change the way it works and how you use it. You can do a variety of things to cut off the incoming angles of shots, create dead zones, or exert your shield's influence over your opponent's shot selection. Regardless of what you do, however, that surface area stays the same. Its percentage of coverage relative to your body size stays the same.
Sure, the length of a sword contributes to its reach, along with the length of a fighter's arm. These two combined give you your static reach - the range at which you can hit someone if you do nothing in an attempt to close the distance between you. The level of influence of this can be changed by footwork. If I move into a position where my static reach now includes my opponent, now I can hit them. It doesn't matter if my sword is 48" or 36" or my arm length is comparable to theirs. Once I am in a position to strike my opponent, if I close too much further, additional blade on the sword or length on an arm that can't aid in generating new or deeper shot angles is essentially "wasted", as it no longer contributes to letting me "hit them better". This is not true for shields, where surface area is always a relevant and consistent factor.
Unless something else steals me away, I actively fight two days a week. On Saturdays I fight from around noon until sundown, and On Mondays from 17:30 until sundown. And this is just straight stick fighting time. There are a few short breaks here or there to hydrate, but aside from that it's almost all uptime. Some weeks there is a third or even rarely a fourth day added to that, occasionally peaking around 20 hours of fight time per week during the summer. This provides constant opportunities to observe what works, what doesn't, and how - across all manner of combatants.
On Mondays, almost everyone uses a 36" sword. It's pretty much the same, standard sword, from the exact same manufacturer. The same sword is used for both florentine or shield fighters. Shield sizes and types, however, differ. Some are punch, some are strap, some are larger, and some are smaller. The tallest person there, who I fight against consistently, has recently tried to use a strap shield that is too small for his body. When he fights with it, I hit him in places that I don't normally have the opportunity to hit him in when he is using an appropriately sized shield. It just doesn't provide the coverage that it should. When he picks up the appropriately sized shield, these opportunities go away. Even though he is considerably taller than I am, and has greater reach as a result, I feel I would be disadvantaged if I tried to use a longer sword. The balance point is wrong for performance shots, it delivers shots slower, and it has a higher recovery time. Simply taking a closing step against this taller opponent manages to remove the only issue I am concerned about (reach), while avoiding taking on all of the aforementioned detriments. In fact, often times I will choke up on the grip of the sword, reducing my range by several inches. This improves the leverage point, and provides additional forearm, hip and leg coverage. This range reduction does not hinder my ability to hit my opponent, because I can easily step in and close that distance. In either case, my area of coverage from my shield does not change, but the influence of my range and shot selection does.
On Saturdays, one of the fighters recently switched from a 40"+ sword down to a 36" sword. Suddenly, all of the shots that he had been unable to land before started landing. His control was better, his balance point was better, and his shot speed and recovery time improved. Having the longer weapon did not in fact give him an advantage, it was the reverse.
These two instances are just scratching the surface of what I have seen in this regard. Are these examples going to be the case for everyone, everywhere, all the time? No, everyone has different experiences. These examples are, however, consistent with what I have seen across several different foam combat sports, in half a dozen states, for two decades. These foam combat sports have no maximum weapon length, and allow particularly large shields. So I have had substantial opportunity to observe how these equipment availabilities that Alliance is now testing play out in a variety of environments, and in the hands of a diverse user base.
It would be much easier to demonstrate what I'm talking about visually in person, but unfortunately we don't have that luxury, seeing as how you're a bajillion miles away. Also, I am trying to hammer this out as I'm being rushed out the door by hangry people who just got home, so if it sounds weird, I apologize, and I'll come back and try to edit it later. I don't feel 100% happy with it is as, but we've come too far, and there's no turning back now!
Basically to summarize, swords and their use should be compared to swords, and shields and their use should be compared to shields.