No it's not. Being creepy and not building up a proper rapport is going to be harassment. Trying to use your status as leverage is harassment. Unsolicited comments or blowing up on someone after a rejection are harassment.
Yes, but "being creepy" is roughly equivalent to "being rejected". You can't determine if your behavior would be creepy without risking the possibility of being creepy.
The exact same behavior, from two different people, will be considered creepy from an undesirable person but non-creepy from a desirable person.
Being creepy is not at all equivalent to being rejected. People who can't tell the difference need to practice reading body language, and develop an understanding of social cues and norms. It's possible, and I'd say normal, to ask someone out, get rejected, and not be seen as creepy as long as you do it in a mature, adult fashion.
Also, it's a given that an advance from an attractive person, in isolation, might not be creepy, but one from a less attractive person would be. The issue is the ugly person has failed to accurately evaluate their own personal dating market worth, which is a negative social signal.
Apps like Tinder seem to helped broker your market worth really well. However in the era of IRC you had to build rapport first. Similarly it’s much easier to fall in love with colleague purely because you spend so much time talking together. Sadly you don’t get that depth in dating apps.
If that was actually the case, you would expect the number to decrease slower (my guess being that online dating would still be increasing at the expense of all others). After all, being creepy or being rejected were already off the marriage numbers anyway, so it wouldn't affect this graph.
It is clear (both through data and through basic anecdotal observation) that dating at work became dangerous to your career, specially if you are a men. So even the cases were it was done in a polite and non creepy way, are rapidly disappearing.
I'm actually surprised it isn't the opposite. I met my girlfriend at work and many of my friends and co-workers have done the same. Its one of the few places (college is another example) that you can build a rapport with someone on a daily basis. If you are around someone you have good chemistry with on a day-to-day basis for months or years, eventually you will get together (no matter what the company policies are).