Yah the paper process is really slow and is a disadvantage for people with very good IELTS scores, WES in hand etc but do not have enough points for Express entry. Well, the express entry is called "express", for a reason
Advantages of paper --
1. No need to panic to submit the application within 60 days. You have a good 6 months.
2. No WES evaluation required.
3. No need of IELTS for many job codes. (This rule is not clear to me still, I may be wrong. I have IELTS anyways, with a CLB9 score, for which I did work hard, but probably is useless now)
4. No need of police clearance for country of residence and country of origin ? Can someone please clarify this? Will this be asked later? Not sure.
Disadvantages of paper
1. Super slow process. You can link your paper to online (Just to get updates).
2. You will need to take a work permit. No employer will ever wait for 1.5 years for PR approval. Virtually, you cannot land with a PR.
3. You get a closed Work permit initially.
4. Tied to nomination and nomination can be withdrawn, for example, if you change employer etc.
So, paper would help some class of people of some age band, who are really good, but sadly don't get invited in Express entry due to various factors.