Because several ecosystems are being destroyed to fuel the oil palm industry. It might be animal-free, but it is not cruelty-free.
The oil palm agribusiness is devastating the rainforest in Southeast Asia:
The two largest oil palm-producing countries—Indonesia and Malaysia—are located in Southeast Asia, a region with numerous endemic, forest-dwelling species. Oil palm producers have asserted that forests are not being cleared to grow oil palm. Our analysis of land-cover data compiled by the United Nations Food and Agriculture Organization suggests that during the period 1990–2005, 55%–59% of oil palm expansion in Malaysia, and at least 56% of that in Indonesia occurred at the expense of forests.
Source: KOH, L P; WILCOVE, D S. Is oil palm agriculture really destroying tropical biodiversity (2008)
This is already causing extinction of endemic species:
Over Borneo and Sumatra as a whole, illegal logging has led to huge declines in orangutans and other wildlife. Where forests are converted to plantations of oil palm or other crops, the consequences are even more serious, with many orangutans starving.
The Sumatran orangutan is classified as Critically Endangered by IUCN. Since 1900, the number of Sumatran orangutans is thought to have fallen by about 91%, with a rapidly accelerating loss towards the end of the 20th century.
By keeping their business away from the developed world, oil palm companies seek to reduce their operation costs by using slavery, child labor and unfair trade:
In the report, Amnesty alleged that children aged from eight to 14 were carrying out dangerous work without safety equipment, were exposed to toxic pesticides and regularly carried sacks of palm fruit weighing 25kg.
Source: Firms such as Kellogg's, Unilever and Nestlé 'use child-labour palm oil' (The Guardian, 2016)
There's also a strong backlash against the sector's PR stunts:
The Malaysian government recently announced that it will ban the conversion of ‘protected forests’ and ‘forest reserves’ to oil palm plantations, and will only allow areas zoned for agriculture to be developed. But it provides little optimism for two reasons. First, it is unclear what type of land has been or will be designated for agriculture. Second, immediately following the above announcement the Malaysian government also declared that it has acquired land in Aceh, Indonesia (45 000 ha), Papua New Guinea (105 000 ha) and Brazil (100 000 ha) for oil palm development.
Source: KOH, L P; WILCOVE, D S. Oil palm: disinformation enables deforestation (2008)