Why is it impossible to get a straight answer as to whether Bitcoin is anonymous or not?
Why is it impossible to get a straight answer as to whether Bitcoin is anonymous or not?

Because privacy is not binary in nature. It is not as if there is some moment at which your information flips from being not-private, to private. Privacy exists on a spectrum, and as a bitcoin user, where you sit on that spectrum depends entirely on the actions you take.
This means that there are ways which bitcoin can be used which afford the user a very large degree of privacy, and there are always ways to use it which afford the user no privacy whatsoever.
Some things that the average user can do to help improve their privacy:

Never give up personally identifying information to exchanges or other bitcoin businesses
Never re-use bitcoin addresses to receive funds
Run a full node to validate the network state themselves, run it over Tor only
Only use wallets which connect to their own full node to query blockchain information
Only use wallets which allow coin control and UTXO labelling
Never look up addresses of interest on blockchain explorer websites (unless using Tor)
Never publicly post any information that could tie them to certain addresses or transactions
Use the lightning network to make payments
Do not send round number amounts when making payments (eg send 0.00104103 BTC, instead of 0.001 BTC)
Use privacy-focused wallet software, such as JoinMarket or Wasabi, to create coinjoin/payjoin/etc transactions .


As a user, you need to decide what level of privacy you need/desire. Maybe following every point on the list above is too much for you, or maybe it isn't enough. There is no 'one size fits all' for privacy, though generally I would recommend endeavouring to retain your privacy whenever possible.
To quote this great article, which I would highly recommend reading:

As of 2019 most casual enthusiasts of bitcoin believe it is perfectly traceable; this is completely false. Around 2011 most casual enthusiasts believed it is totally private; which is also false. There is some nuance - in certain situations bitcoin can be very private. But it is not simple to understand, and it takes some time and reading.