Companion planting-Is it so important ?

I have a very limited space in my raised bed and have planted out in order from left to right in rows:

White Onions
Broad Beans
Beetroot
and going to plant runner beans in the end when ready.

In the other bed:

Red Onions
Peas.

Now I have just read that certain veg can't be grown together very well and it's sod's law mine are mixed in the wrong way. As I don't want to rip them out (I can't anyway for lack of space) has anyone else found that it doesn't really matter what is next to what. I mean, how can something know what is growing next to it ?

I was going to post before Yorkie nipped in that the classic no-no is onions and peas.

Personally I never give it a thought and I'm sure I've done it in the past with no ill effects.

I don't think it's that, it's more to do with alledged chemical release.

For instance, per sturmsoft.com:

"Some plants cannot abide growing adjacent to others, for example peas and onions. The pea rhizobia are sensitive to root exudates from the onions. Knowing this beforehand prevents problems."