What special functionality does "Leads" have that Contacts / Deals doesn't have?

What special functionality does "Leads" have that Contacts / Deals doesn't have?

There are many questions in this forum about regarding "Leads => Contacts/Deals" conversion. I am in the same boat and get very frustrated having to jump through multiple hoops trying to figure out the lifecycle of a lead (there is loss of information and visibility when a lead is converted).

I am planning to stop using the leads module completely and create Deals out of all self-signups coming for my SaaS product. Before I make this radical move, I wanted to understand the pros and cons of doing this from others who've done the same:

  1. At a broad loevel, does the Leads module have any extra features (fields, reports, email, triggers, workflow rules, etc) that aren't available in the Deals module?
  2. Can one introduce a concept of "Junk" deals which are not shown in the pipeline reports and are not used while calculating sales funnels?
  3. Can the same Deals module be used to track/report funnels of 3 separate product (each product having a very different sales/purchase behaviour)? Or should one "duplicate" the deals module and call it "Deals - Product 1", "Deals - Product 2", etc?
  4. Can a Deal be created without necessarily creating an Account or Contact? What are the downsides of doing that?
  5. What is the advantage of creating an Account + Contact, especially for a simple sales cycle where the purchase decision is made within 30 days of the self-signup happening (i.e. no multi-year/multi-stakeholder conversations)?
  6. Can a Zoho Sign document be automatically sent to a deal when it is put into a specific stage, say "Contract negotiation"?
  7. Can the deal be synced with Zoho Subscription and Zoho Desk once it is marked as "Won"?
  8. Can Deals be assigned on round-robin basis?
  9. Can workflow blueprints be creating around Deals?
  10. Anything else one should be aware of?