Google doesn't mistake B for T2.

When people design the software that runs a writing site, they normally equate a subtitle with H2 and a title with H1. (I used to be a web designer).

Google uses titles and sub titles to determine what the article is about, so they are keywords, and they will rank your article according to that.

If you use bold, they ignore it. It isn't taken as keywords. It's discouraged by content writing sites where advertising is used to pay the site. So if you want your writing to rank on Google, you have to format according to Google rules. Getting to number 1 for a particular keyword is the aim.