Not really. Takealot and Kalahari use vouchers to push sales through and not to acquire new customers. The e-commerce customer base is pretty static with a predictable growth rate as internet becomes more accessible and people become comfortable with online ordering and payments. With any business you will initially pay an acquisition cost to sign up the customer and then need to create some stickiness to keep the base. Everyone thought that with the Takealot/Kalahari merger their customer base would be 1+1=2, but in fact it was more like a 1+1=1.2 as most Kalahari customers already shopped on Takealot and vice versa.
Vouchers result in instant cash burn and invite fraud as people will sign up multiple accounts and this results in over-inflated figures of a customer base. When a business subsidises shipping and then throws in a voucher, a product is not even sold at break-even, but mostly at loss (what you guys do not take into consideration is the OPEX burn when it comes to running the business with a few hundred staff, warehouses as well as millions spent every month on radio/SEM etc). When you analyse price-points you will find that the margins are very small (although Takealot does get preferential pricing from the distributors due to volume) and neither Kalahari nor Takealot has ever broken even since their existence. IMO, the 1bn Rand fund run from last year would have been burned through by the end of this year and I will not be surprised to see another big fund-run come in within the next few months.
Bottom line is that loyalty in e-commerce is not based on how good your service or how cool your brand is, but is merely based on if your product is sold for the lowest possible price compared to competitors (or if you play in verticals which others can not support).