Sure I've heard that definition. Yet it describes a "symptom", and not a process which it is a manifestation of. I just feel like the discussion about "introvert" is extremely shallow: here is a child, she's an "introvert". And it ends at that. We've started to use the word as a noun, but should we?
I think I used to be not introverted as a child. Then, as I experienced the pressure of moving to another country during teens, I became more introverted. And now I am not.
I think it's mostly that introversion vs extroversion are closer to what the post you are responding to, while more often then not, social anxiety and shyness are conflated with introversion while that is not necessarily correct. Introverts exist that are comfortable interacting with groups of people. Being "drained" by social interaction doesn't mean that they don't enjoy it or that the draining is stressful. I think of it like a timer that counts down until you'd prefer not to be in social situations anymore.
That being said, I consider myself extroverted and I experience an opposite effect. After being in non-social situations for a long enough point I get to where I don't care what specifically I'm doing I just want to do something social. After a day of reading or individual pursuits I might feel a little stir crazy and text anybody I know to do anything from go get a bite to eat or hang out with no particular activity in mind.
One is not set in stone as being an introvert or extrovert. People can change and it really comes down to what doesn't drain/take energy to do... being around people and stimulated or being alone or in a quiet environment.
As someone who has "battled" introversion for much of my life, I can agree with the sentiment of the statement. I say battled because I feel like when I say I'm an introvert, people around me scoff because they feel I'm the farthest thing from an introvert. I'm happy to hold court with those who want to take part in my conversations and I strike up conversations with complete strangers on the train... I'm not particularly shy per se and I don't lack for confidence in my abilities or place in the world. But if I don't get "me time" on a daily basis, it would be like other people going without sleep. It's time to allow cognitive processing, but unlike sleep, it's conscious cognitive processing. I need this time to make sense of the world, ideas that would otherwise never be given enough thought to understand or process.
Your statement has caused me some self reflection and I think I agree. I can't say upon reflection that I am either an introvert or extrovert.
I find many types of personalities draining - as I'm sure we all do, even extroverts. I need time away from these personalities to recharge. Preferably time on my own to do my own thing, tinker, watch the world go by, but most of all think, uninterrupted or intruded upon.
There are types of people that suck energy from other people. Those that require constant attention: Those that feed off your attention and will do whatever they feel they need to in order to absorb that from you. That is mentally exhausting to most of us. For me this includes people I've labelled (for better or worse) show offs - the 'look at me, don't you agree how clever/talented/awesome I am?' types.
There are also types of people that recharge you. Those that give freely of their energy, but don't require your attention. They happily send their energy your way and then let it go, content to go back to what they were doing without a need for constant reassurance or input from you. They bounce in and out of conversation, make you laugh, engage with you, but don't constantly sap your energy. Just as content to share space and not talk as they are to converse with you.
Having to be around people that constantly need or fight for your attention, always making noise, talking just to talk, interrupting your thought mid sentence; those that never appear to have any respect for the directives: If you don't have anything to say that improves upon the silence, don't say anything at all; and say as much as you can in as few words as possible.
These are the kinds of people that drain everyone... we label people who can't put up with this for very long 'Introverts' and people that are this 'Extroverts' :P I say that tongue in cheek, I don't believe this is the definition of extroverts... extroverts just appear to be more immune to the energy sapping effect of this type of behavior.
In reality, I don't believe that any of us are either of these things in totality. What I do believe we are, are people with varying levels of tolerance of other people invading our personal space or mental bubble uninvited; intruding on our thought processes and spoken word with few manners or thought for those on the receiving end of that behaviour.
I think I used to be not introverted as a child. Then, as I experienced the pressure of moving to another country during teens, I became more introverted. And now I am not.