Pure mdma more dangerous than X tablets?

[actarus]

On a websites (streetdrug.com) swim found this:
"When used alone, MDMA is dangerous. It is even more dangerous when used in combination with other substances, as the physical and psychological effects are difficult to determine or predict."
It doesnt sound right to swim, since its very very often really hard to exactly
know what theres in a tablet and therefore forecast the effects.
And isnt pure mdma supposed to be safer (as for effects as for health issues) than tablets?