Knights of the Reliquary

[Dstyle1]

Ummm... No. The pros frequently diversify their win cons in decks like bug and Mavericks. Legacy is more diverse than modern, so having a couple one ofs to diversify your wins is a thing.

From playing GW knights in legacy most of my sideboard slots were used for countering other arch-types typically encountered at my local meta. I am not sure what alternate win cons would you suggest for a W/g Knight deck, to stay on topic with original post.

After thinking about your post for alternate win cons. The thing that allows for alternate win cons is something that is very prevalent in Legacy and that  is the ability to search. U decks can play 1 of because of brainstorm, ponder, cards like this.  Mr_Farenheit can play a single Craterhoof or progenitus because the deck has search {natural order} or {worldly tutor}.

The greatest flaw that playing white has had is its severe lack of search. This is why the need for playsets of creatures. Without search playsets allow for more consistency in your draws. In this type of tribal deck your win con is going come from your knights. Adding anything to increase your searching ability ie {sensei's diving top} will dilute your creature base which is where your power comes from.

The sideboard I commonly used was a tutorboard. Any DnT players know about this as you play one-ofs of Enchantments and Artifacts and 3-4 {Enlightened Tutor}  which allows for search. Plus some anti-combo hate usually the blue trap spell.

I guess this debate all flows from whites lack of search which is more semantics.

[Mr_Fahrenheit]

What you said there, while it makes sense, is not what you stated earlier. I was merely stating that playsets of cards and only sticking to your tribe is not always optimal, whereas you originally stated that it is. After actually explaining yourself, what you said makes sense. Perhaps in the future you could actually explain your reasoning, and which specific cases it is actually true for, before making blanket statements that are not supported by evidence outside those specific cases?

[Dstyle1]

In most tribal instances it's true:
Going through the color wheel;
Red/goblins has search and draw in the form of other goblins {goblin matron} and {goblin ringleader}

Blue/merfolk: has blue spells to dig but I think most of the power comes from other merfolk {Merriw reejeey}?

Black/zombies: has search in the form of black tutors, but from my experience ppl would just rather draw another zombie

Maybe vampires?

White/Knights: no draw, no search

Green/ elves the only tribe that gains power from outside the tribe, and Is able to stay in color. This is probably due to the creature search and inherent creature boosting abilities from other green creatures that green provides.

So while I believe my statement is true for most cases when running a tribal themed deck you would want consistency of drawing more of the tribe due to the fact your playing a lord/lords that boost the team.

While elves appears to be the exception rather than the rule.

Think of it this way pretend there is no worldly tutor and no natural order. Do you still play a one of progenitus or craterhoof behemoth? Would you play them at all, or replace them with another elf lord?

[Mr_Fahrenheit]

It would entirely depend on the way you wish to construct your deck. There are arguments for both, depending on what you are trying to achieve with your deck. You can go beatdown, and play ezuri, in my case it would be the first elf lord in the deck. But even in that situation I would still run a craterhoof, as he benefits from the mana ramp that the deck generates. You could also run {regal force} to generate card advantage. Also not an elf, but can be used in addition to or instead of tutors.

My point is, you can build a tribal deck that is still competitive without absolutely having to stick to playsets of cards that are part of the tribe. I am not discounting what you are saying, I am simply saying that it is not the absolute be all and end all that you are claiming. It is simply one of many ways you can construct a deck.