Fairly straightforward. In order to steal devil fruits, Blackbeard Pirates galavant (in Burgess’ case, hunt) with a bag full of apples/some other fruit in order to capture devil fruits. This sparked something that I didn’t notice before… Doc Q was doing the same thing way before the timeskip, as he offered Luffy an apple and said he was ‘lucky’ because he chose a fruit that didn’t make him explode.
Why else would Doc Q, a member of the Blackbeard Pirates randomly have a basket full of apples? This may be his own tactic of stealing devil fruits as opposed to Burgess’ more animalistic manor. Anywho… What happens when a devil fruit user consumes another devil fruit? Yes, he/she explodes, and I think that is what Doc Q was referring to when he said Luffy was lucky not to explode.
Pretty simples, BB pirates have different methods of killing devil fruit users in order to steal their fruits via having a multitude of apples/other fruit in a nearby bag or basket. Anyway like I said I’m not sure if anyone noticed these Doc Q or Burgess details before so I thought I’d just leave this here.