Simply put, WordPress.com is that wordpress engine that hosts your blog, offers you a “free” blogging platform with a .wordpress subdomain name. Meanwhile WordPress.org is a community of web developers, working continuously on the open source WORDPRESS script, making it available for use by anyone, that would have to host it, by his/her(self) making use of a third party hosting.
I’ll be concise with this.
1.) It is not cost effective.
To use literally almost all the features that would really make your blog a blog you’ll have to pay, to even park your own domain name which is absolutely free on blogger, you can’t until you upgrade to the premium plan. Note: the premium plan does not give you free domain o. And most of the payments are mostly nothings $19 upward.
2.) Not Theme Versatile.
Premium Plan or not, you’ll not be having a variety of themes to choose from, just a few and you can’t really upload a theme of yours (custom). It’s worse in free though, and premium plan will only offer you some bits of customization to themes, stuffs most other platform give freely.
3.) Cpanel Is Not Mobile Friendly.
You think you’ve seen worst, wait till you try making a post om mobile. You’d literally have to fetch baskets of waters for building of a house
4.) Plugins Malutrition
On wordpress.com, you don’t get access to amazing plugins like it’s .org. Only a few insignificant ones become available to you after you even upgrade.
5.) Annoying Advert Modes
The advert protocol simply put is outright ridiculous! They’ll literally spam your blog with not well structured adverts when you are running the free plan which can make your readers get irritated. And if you upgrade to paid plan, you can’t just monetize the blog yourself, you’ll have to apply for it, and agree to split gains that you advertising yields 50:50.
There are more reasons though but I’ll leave it here, 5 is enough for a warning, they’ve got perks, yes, but the side effects flawlessly nullify the perks.
Have a great day, be wise with choices.