As an example see the great oxygenation event. Where bunch of selfish green algea pumped waste product into the atmosphere killing almost all anaerobic life.
Then there is the carboniferous period where trees grew so much that due to lack of lignin breaking fungi they basically sucked out all CO2 from atmosphere causing global glaciation and killing themselves in the process.
Life has been crapping itself since the very start. We are no worse than others, however we have the chance to be better.
This platitude is actually interesting in this context. It connects multiple threads:
* One of the previous major extinctions was the Oxygen Holocaust [1], caused by photosynthesizing cyanobacteria. It killed pretty much everything alive back then. And turned our Earth into a snowball to boot.
* This oxygen is a major contributor to CANCER, via free radicals etc. It leads to a faster (and more ruthless, more side effects) metabolism, enabling evolution of highly reactive creatures such as us.
* And trees, the "speaking organisms" under discussion, are one of the major producers of this highly volatile, carcinogenic O2 substance.
Tongue in cheek? Maybe. But hopefully no worse than the naive "humans are a cancer to the planet".