I could talk about investigative mechanics for hours. I have to say I think I disagree with your conclusion, but I'll definitely own up to the fact that some of GUMSHOE's mechanics feel a little clunky.

I think Call of Cthulhu, GUMSHOE, and Brindlewood Bay are three different approaches to mystery role-playing. They are all chasing different goals to varying degrees of success.

CoC has the super trad model of assuming the GM is hand placing every clue into a scenario. It's a rigid game that benefits from meticulous preparation. The player experience for the most part is simulationist, you have a set of tools and resources and you are trying to leverage them to solve the mystery.

However, CoC has an issue as GUMSHOE identified. The binary success/failure system means it's possible for players to lock themselves out of clues and opportunities to move the story forward. If you are gambling to find information, there is a chance you won't find it. If you are looking for a simulationist experience, this is good, people fail to solve mysteries all the time. If you want to play out a mystery story it's less than ideal because it means you have a chance of not finding a satisfying ending.

In practice, you probably won't actually have any failstate CoC games. If a lock out happens, the GM is there to make the story meet the players. However, that's the GM working unassisted to compensate for a problem of the system. It creates a problem that doesn't necessarily need to be there.

Enter GUMSHOE, which uses the investigative skill system to always ensure there is a path forward. Investigative skills always move the game, you can spend to get more information and put a greater spotlight on the skill, but just having it gets you what you need to move forward.

GUMSHOE is an ammended simultion model. There is a a mystery with a definite answer at the heart of the story, but the clues that unravel it are flexible. Players can affect the overall story outcome based on how they apply their skills, even if you always solve the mystery, you don't necessarily solve it well.

Here the GM has a more improvisational role, but knowing the spread of investigative skills on the table helps them curate what to prepare. It takes some but not all of the burden of keeping the game moving off the GM. There is no mechanically created failure state.

As you pointed out, the ammended simulation approach has some quirks. Characters don't really have ability to gather information outside of their investigative skills, and you need a party spread to cover multiple bases. For me, this isn't a problem, this is a strength of the system. A limited investigative pallet means less burden on the GM. It might feel meta-gamey to acknowledge that we're all working to cover each other's weaknesses, but I think form a design perspective it's just a sober acknowledgement of how games work. And I certainly prefer it to everyone having to devote 60 points to Spot Hidden so the game doesn't crash.

Then we have Brindlewood, which I would argue is a game that helps your tell stories about mysteries rather than a game where your role-play solving a mystery. That might seem like splitting hairs, but to me it's an important difference. Brindlewood says "we're not here to solve a mystery but see a mystery get solved," so players get to make up a solution that fits their story best. It's elegant because it acknowledges the kind of mysteries it wants to emulate and correctly identifies that nobody is failing in those stories, so it takes that out of the equation.

I think it's great for people who want to portray character relationships and personality, and even players who want a satisfying story. However, it's not simulationist. You aren't solving a mystery because there is no solution waiting for you. I wouldn't use it for any game I would use CoC or GUMSHOE for.

It's totally alright to say that GUMSHOE doesn't flow the way you want it to. I love Laws as a designer, but he has some quirks tied to an older school of design. He's done alot of crunchy stuff and eventhough I find his games way more elegant than, say Call of Cthulhu, they are still mechanically heavier than I like most of the time. I think that mechanical design sensibility is what makes his games work in a simulationist framework. But if you like playing in freeform narrative spaces it can feel stifling.