"You’ll bring work home with you more often than not."This happens regardless of managerial position. The only difference in management role is the lack of direct control, which when not yet internalized, keeps the mind in denial and torment (especially at home). Yet, demands from above that don't take into account the limits of control, happens a lot in business environments, unfortunately, for both managers and ICs. This (should be obvious that) is a source of stress, that gets spilled outside of work hours.
"You’re not «part of the team» anymore."
Most often, the managers are the ones choosing to distance themselves from the managed lot and seek the company of other managers or people in the power network. Otherwise, as an anecdote, I know a manager that used to organize free time events for his people all the time, like a true socialite (and getting in everyone's heads when given the chance). Therefore, from what I've seen, given the power (and resources that comes with it), being "part of the team" becomes an unchallengeable choice.
"You need to be careful with every word."
This has more to do with being an adult than being a manager. If nothing else, the power that the managerial position brings is not reflected only in the weight on the shoulders that responsible people feel, but also in the means to control the frame of interaction and with it -- the means to get away with a lot (even with abuse), and afford not to be that careful (with the managed).
"You’ll probably feel very lonely."
It's a choice, an empowered one even.
"You will carry knowledge you cannot share."
This is true. But, ICs have to sign NDAs too.
"You need to network and understand the business."
This is more of a choice that leads oneself to a successful career path, so it's a thing that makes sense for managers (with freed attention and time on their hands) to do. It's also the reason behind the above mentioned "not part of the (powerless) team" choice.
"You will miss being an engineer."
I wish this to have been true for a lot of managers out there, but it isn't. Most of the managers are ambitious people, with clear career plans, that haven't gotten in the industry for their passion of software engineering. Being surrounded by this type of people, "miss being an engineer" comes out just as the right thing to declare for others, or... childish and out of place if one truly believes it.
"You will not get the training you need."
This is just something I hear from managers that haven't yet made peace with the nature of having only an indirect control. Sure, the management game(s) require some learning, but the bar one has to reach is not about its technical aspects mentioned in the article. It's about acting as part of the core group of company (like part of command in an army). You aren't supposed to get training on this bit, you're supposed to "get it" on your own (and play ball once you do).
"You need to be the adult in the room."
Unfortunately, I've seen too many times when the managed ICs are treated like children, and "being the adult in the room" was a designed role to be assumed by the manager as a consequence. Yes, management position gives you a lot to play with, even these kind of unsavory social games. It also gives you the power to demand adult behavior from everyone in the managed team, if you choose to do so.
"You need to learn how to sell." "You must learn how to manage up."
Most of this part is just busy work. You were IC before (becoming a manager), you know how little need you had back then from your manager to get you excited to do your work. Now, the managers above you were once in your shoes too, you can bet they see right through whatever you serve them with, and more. The other departments have their own readings, independent of whatever biased information you insist to provide them. Yet, the show must go on, something you have to "get it" on your own. It's because, among other things, this is what makes true the last mentioned bit -- "being a manager can be fun and fulfilling".