The word 'monopoly' may be not quite right but the premise is.
The notion of 'there are other choices' is simply not the measure of a competitive landscape in systems with very high switching costs, incumbencies.
The pedestrian view that we have for 'competition' is 'retail' - you move from one shop to the next.
Big Industry is nothing like that.
They entrench themselves, with standards, process, procurement, brand, strategic leverage at the Executive layer, regulatory capture.
My local 'pharmacy corner store' has the same 10 chocolate bars my whole life: KitKat, Coffee Crisp etc. It never changes.
Does anyone in the world think that KitKat has some magical 'product quality' beyond the 10 000 other variations of chocolate?
No - they have 'market power'. They control distribution, they have deeply entrenched relationships with retail, they have relationships with coco producers, which shows up in a lot of ways.
If a buyer want access to the release of the 'New Swiffer' - you can't just try to 'drop our other products' like KitKat, besides, consumers have not been trained on a different product.
Consumers have seen a lifetime of KitKat ads, we don't necessarily like it, but it's a known quantity and we basically 'submit'. There are other choices, but a bit further back, a bit more expensive, a bit more unknown.
The very fact that 'chocolate bars' are unambiguously a commodity - and yet - there is no 'apparent broad market' should well serve to starting thinking more about how these systems work.
Google pays Apple an absolute fortune to be the 'first choice' on iPhone.
Google pays a fortune to create/control Chrome - which makes $0 in revenue, but which is a critical distributional component.
So your kids use 'something else' because they're in a situation where they can - but when the go to the office - do they make their own choice? No - IT does.
If IT wants to move away from just Word - then they loose deep integration with so many other things: MS Office is designed to be fully integrated precisely to thwart off all of those individual incumbents - the only way someone can make inroads, is on the margins with something really powerful, like 'Airtable'. Even then, it's relatively niche.
Combine that with the Operating System, which integrates deeply with chipsets and scale, and you can see the power.
I think that Slack is essentially a superior product, but the law firms, energy companies, gov offices are going to be sold 'Teams' and that's it. I know a lot of people who use teams and have literally never hear of Slack.
Slack is the 'niche chocolate bar in aisle 3 that costs 20% more, that they have never tried and not sure about - just buy KitKat'.
I have colleagues - very educated - who only use Copilot for AI - they think that's AI. They're not allowed to use anything else - because 'security'. Copilot is a ridiculously inferior product, not only do they exist in the ignorance of that, they actually think it's 'great', partly because 'It's Microsoft'.
The power of 'Brand at Scale' is really hard to fathom - managers and executives particularly are moved by this. They probably believe in institutional power and legitimacy more than anything and so MS because a 'hard default' that becomes difficult to overturn.
If there's a problem with some 'uppity gov. official' somewhere - MS can make discounts, steak dinners, custom integration, talk to people higher up in government, and make a strong case as why disrupting the 'default' should not happen.
ERP like SAP ... are just interminably integrated, and AWS/GCP are practically different products they are so different.
All of that is the tip of the iceberg.
There is no 'free market' in the way our instinct may apply, which is mostly derived from our 'retail' position in the value chain - the market operates a bit more differently at that level.
At that level 'Market Power' is the dominating factor, and 'product' is always second, generally things need only be 'sufficiently good'.
MS is an ok company and can create 'workable products', Google has some 'great' (and some terrible products), it's all they have to do to perpetuate - there is absolutely nothing anyone could do to displace them without some non-market force (aka government regulates competition).
If this dependency becomes a problem , and I would suggest finally in 2025 it is, then the only way out is coordinated action.
After all that I just said, the true power of institutionalization is not always hugely critical: if KitKat disappeared tomorrow nobody would care. If MS word was removed ... and everyone just choose something else, the world would not miss a beat. I truly believe that if we all woke up tomorrow and had to use Bing, it wouldn't matter that much.
Aside from major market disturbances, like AI in which those 'adept players' will probably be ahead anyhow, then it takes coordinated action to disrupt these systems.
It's much better to view those things through the lens of 'power' and not so much 'product', unless 'product' is absolutely decisive, novel, and/or it exists outside of locked-down value chains.