Hi, your average Turkish guy from Berlinhere, please be easy on the downvotes. I am only sharing my knowledge(i.e. how I know it.) If there is any person disagreeing, or has opposing evidence, please share it with me. I am more than willing to read and learn if I made mistakes.
And lastly, I would be greatful if you read until the end.

I believe the idea that Ottomans 'Colonised' the Balkans as a far fetched exaggeration, if not a accusation outright.

First thing to understand is,There has been Multiple types of empires, which were established around certain ideas, such as trade empire of Dutch, religious empires of caliphates, state/beurocracy empire like Ming from china and even dynastic feudal empires of Angevins(i.e. anglo french nobles). Of course lastly, Conquest; An empire which is heavily invested in war and the economy driven thanks to war. Such as Mughals, or more fittingly for this case, Ottomans.

Lets be fair and Square. Ottomans was a empire, which revolced around the goal of 'conquest'. This has been their motivation for most of the time, at least until Tulip age ' Lale Devri.). And to be completely honest, Ottomans did place turkoman tribes to the conquered teritories(iskan sistemi), both to solidate their gains, strengthen control, and develop/improve their agrarian economy and timar sistemi.

But it has to be pointed out, and this is VERY IMPORTANT IMO, this policy is completely different from what we categorize as 'colonisation', since the outcomes of the process is very different. The Conquest of Ottomans in balkans was not followed by any forced relocation, mass subjugation, and only slight cases of forced conversions. The conquests of Ottomans however, did not result in Mass Slave Estates, run only for profit. I.E. Colonial territories, which was most prominent in 18th century.

A slav's life in 18th century Ottoman controlled serbia, could not be compared to the sheer suffering people had to endure under colonial powers. be it spanish in south america, dutch in southeast asia, english and americans in north america, french in carabians. And of course, most notoriously all of europe in africa.

Only example/objection that easily comes to mind, and contradicts my words is (at least to my knowledge, please correct me if I am wrong.) devshirme/devşirme system. A tax system where people could give their children to state, in return for a tax cut.
Which, if I am not mistaken, was very rarely practiced, since the number of janisaries in Ottoman empire never exceeded 100k, whilst population in balkans was more than 4 million. so even if every houselhold in the entirety of balkans consisted of 10 members, that would still mean only 1 in 4 households. a 3:1 ratio was not majority last time I checked math.

But, I like to point out that, even within janisary system, which some may consider the worst outcome, a common born peasent boy could become a army commander, or a statesman (Entire Köprülü family is the most famous example, being of albanian origin, they are still one of the richest and most influencal families in turkey.) this was something unheard in europe until napeleonic era.

And last thing I want to mention is, only as a sidenote, Ottomans built nearly ALL of their infrastuctures in balkan teritories; roads, trade markets, mosques, courthalls, and even weapon and ammo manufactures centers(such as baruthanes(gunpowder houses) of greece. No colonial power has spent really THAT much in their colonial territories. just look at any former colonial nation, and tell me what you can see the colonisers left.

This may sound like a tinfoil hat theory, but to be honest, I geniunely think this is one of the trends when some people claim some shit on internet, and people with less knowledge just nod their heads and go through with it.