For those not familiar with the term, phonotactics is the linguistic phenomenon which controls which structures of words are acceptable.
Let's make up two words. Clestrath and Pkan. Try to pronounce them. Assuming you're an English monoglot, you probably found the first far easier to say than the second.
This is because the first complies with English phonotactics - even though it's longer, the two consonant clusters "cl" and "tr" are acceptable.